Improving Reading at Scale: Evidence for Structured Literacy Instruction in Argentina's Primary Schools
Phase: NA
Conditions: Children's Early Reading Development
Sponsor: Florencia Salvarezza

 
“Improving Reading at Scale: Evidence for 
Structured Literacy Instruction in Argentina’s 
Primary Schools” 
 
NCT Number: NOT YET ASSIGNED 
 
Date: 01/28/2026
 
1 

 
 
Improving Reading at Scale: Evidence for Structured Literacy Instruction in 
Argentina’s Primary Schools 
 
Florencia Salvarezza. Universidad de la Ciudad de Buenos Aires and the UConn/Haskins 
Global Literacy Hub. Florencia.salvarezza@udelaciudad.edu.ar 
Dan Steinhof, Department of Psychology and Department of Cognitive & Brain Sciences, 
The Hebrew University of Jerusalem, dan.steinhof@mail.huji.ac.il  
Elizabeth Zagata, Center for Education Systems, WestEd, ezagata@wested.org ORCiD: 
0000-0003-1208-2691  
Luiza de Melo Carvalho,  University of Connecticut, Department of Psychological Sciences, 
Storrs; 
UConn/Haskins 
Global 
Literacy 
Hub. 
luiza.carvalho@uconn.edu 
ORCiD: 
0000-0002-2571-9762 
Augusto Buchweitz, University of Connecticut, Department of Psychological Sciences, 
Storrs; 
UConn/Haskins 
Global 
Literacy 
Hub. 
augusto.buchweitz@uconn.edu 
0000-0003-3791-7472 
Noam Siegelman, Department of Psychology and Department of Cognitive & Brain 
Sciences, 
The 
Hebrew 
University 
of 
Jerusalem, noam.siegelman@mail.huji.ac.il, 
0000-0002-5005-4838 
Kenneth R. Pugh, University of Connecticut, Yale University School of Medicine, Director of 
Research, Haskins Laboratories, kenneth.pugh@yale.edu https://orcid.org/0009-0001-0157-838 
 
Maureen W. Lovett, The Hospital for Sick Children, the University of Toronto, the Yale Child 
Study Center and the UConn/Haskins Global Literacy Hub. mwl@sickkids.ca.  
ORCiD: 0000-0002-7556-8309 
 
 
 
 
 
 
 
 
2 

 
 
Abstract 
Purpose: 
Throughout Argentina, schools have struggled with the teaching and evaluation of 
foundational literacy skills. We report results from a longitudinal controlled evaluation of a 
teacher training and structured literacy program on foundational literacy outcomes in 
multiple Buenos Aires schools. 
Method: 
From 8 intervention and 7 control schools, 537 children participated: 258 intervention and 
279 control participants. All were native Spanish speakers entering Grade 1 and tracked for 
two years. Teachers from intervention schools were provided over 20 hours of professional 
development yearly in Aprendo Leyendo (AL), a Spanish-language structured reading 
program. AL was taught in Grades 1 and 2 intervention classes, and control schools used 
their usual reading instruction. Performance data were collected four times: the beginning 
(T1) and end of Grade 1 (T2), and the beginning (T3) and end of Grade 2 (T4).  
Results: 
Intervention students demonstrated significant posttest advantages on several reading and 
reading-related skills, with better T4 performance than controls on passage comprehension 
and letter-sound naming. Differential growth on two word reading fluency and one letter 
naming fluency measure were also revealed, and on two component skills, phoneme 
segmentation and set for variability. Individual differences analyses showed that, generally, 
children with better component reading skills at T1 demonstrated larger intervention gains. 
Conclusion: 
Results demonstrate the positive impact of structured literacy Professional Development, 
PD,  and instruction in the early grades and demonstrate that better literacy outcomes may 
be achieved. Findings support continued use and scaling of structured literacy initiatives to 
improve reading outcomes for children across Argentina. 
 
Word count = 250 
 
 
3 

 
Introduction 
Evidence-based foundational literacy practices in Latin America and the Caribbean 
In recent years, Latin American and Caribbean countries (LAC) have demonstrated  
significant improvements in early education access and school enrollment. Out-of-school 
rates (3%) and school completion rates (94%) for primary education in the region have 
approached near-universal levels (UNESCO, 2024).  However, most LAC countries do not 
assess early literacy outcomes; in primary education, for example, about a quarter of the 
region has no reliable national assessment (UNESCO, 2024). Even with use of these 
assessments, there remain many obstacles to effectively teaching early literacy skills. In 
Argentina, only 33% of sixth graders have achieved the minimum proficiency level in 
reading (APRENDER, 2023).  
Part of the instructional challenge in LAC countries is related to a historical failure to adopt 
systematic structured literacy programs and phonics-based early literacy approaches 
(Stone et al., 2020). There has been longstanding resistance to the Science of Reading, 
from within the Schools of Education, and many practical challenges to implementing and 
sustaining evidence-based policies.   
There is evidence, however, of some potential solutions through an investment in teacher 
training in evidence-based practices. Teacher training is a cost-effective strategy for 
promoting evidence-based foundational literacy practices. In Honduras, one of the poorest 
countries in LAC, a USAID report revealed a cost of only US $1.00 (one US dollar per year 
per student) to achieve the same improvement in student performance that other 
strategies, such as class size reduction (US$23.00 per student) and implementation of 
end-of-grade assessments (US$52.00 per student) accomplished at far greater cost 
(Rhodes, 2021).  
In the present study, we investigated the effects of teacher training and of the 
implementation of systematic, phonics-based instruction in the province of Buenos Aires, 
Argentina. We compared the early literacy performance of children in schools that adopted 
the program with that of children in control schools that used business as usual, 
non-phonics based instruction. The primary goals were, first, to carry out a longitudinal 
evaluation of an evidence-based teacher training program in multiple schools in Buenos 
Aires; second, to assess the feasibility of the program and its acceptance by teachers; and, 
third, to examine potential effects of the program on foundational literacy outcomes among 
early primary education students. The longitudinal nature of the study design also permitted 
the investigation of additional research questions regarding individual differences in 
children’s response to instruction and an examination of early predictors of reading 
outcomes. 
What works: Cumulative, systematic, and explicit structured literacy instruction 
Systematic and explicit structured literacy instruction is the most effective way for teaching 
children to read (see, e.g., Castles et al., 2018; Ehri et al, 2001). This begins with a 
phonics-based curriculum that teaches mappings between letters and sounds, letter 
clusters and sounds, variant letter-sound symbol mappings, and decoding strategies. 
4 

Ideally, this approach treats decoding and spelling as reciprocal processes to be learned 
(Kim & Zagata, 2024). Such instruction serves as a foundation upon which a 
multidimensional reading system is built. It should be noted that phonics-based instruction 
is a necessary, but not sufficient, approach to literacy instruction. It is essential to establish 
the foundational layers of a reading system but other aspects of written language structure 
also need explicit attention.e,g., orthography, morphology, semantics, and syntax. 
 
Phonics-based structured literacy instruction is the most effective choice for beginning 
reading instruction independent of the regularity of the mapping of speech sounds to print. 
Among world languages and their writing systems, there are more “opaque” orthographies, 
like English and French, with more variable mappings between speech sounds and letter 
combinations, and more transparent ones, like Spanish and Finnish, which have basically 
univocal letter-sound mapping (Seymour, 2003). Regardless of these differences, the path 
to effective early literacy instruction is the same (Caravolas et al., 2012, 2013), and the 
predictors of achievement are remarkably similar. 
 
Brain imaging research has also provided evidence that the integration of effective mapping 
of oral and written language is the basis of fluent reading. It has been shown that the 
brain's network of areas that support reading is constrained by previously-developed 
speech-processing circuits common to all languages. The more the brain circuitry for 
speech and for reading converge, the better the actual reading fluency and comprehension 
of an individual, across multiple languages Rueckl et al., 2015). These findings are 
compatible with the findings that systematic and explicit teaching of phoneme-grapheme 
correspondences, syllabic structure, and morphological patterns effectively support the 
learning of foundational literacy in Spanish.   
 
The struggle with teaching children to read in Latin America 
Schools in LAC countries have struggled with the teaching and evaluation of foundational 
literacy skills. There is a scarcity of both successful evidence-based efforts in the region 
and rigorous scientific evaluation of early literacy programs (evidence-based, or not; see 
Stone et al., 2020 for a review). Randomized controlled trials and large cohort 
observational studies in early literacy and in education are a rarity in Latin America (Stone 
et al., 2020). The challenge for improving foundational literacy in Latin America includes the 
need both to provide teachers with effective, evidence-based professional development 
(PD) and to establish rigorous scientific scrutiny of reading instruction and its efficacy.  
One outlier in the region has been the program (and associated study) Aprendamos todos 
a leer (Márquez de Arboleda et al., 2020). This project provided evidence-based teacher 
training and instructional materials to schools in Colombia, and its efficacy was evaluated 
rigorously, in 70 schools and with 2,100 students. The study of Aprendamos todos a leer 
showed that children whose teachers were trained to use the program achieved 
significantly greater gains on early literacy outcomes than their peers, and these differential 
gains persisted over the years. In other words, students of teachers from the program 
outperformed their peers in first grade, and continued to outperform these peers through 
second and third grades (Alvarez Marinelli et al., 2023). These findings are encouraging 
5 

and raise the question of whether such innovations can be adapted and transported to 
other countries and cultures. 
The need for evidence-based early literacy instruction in Buenos Aires and 
Argentina 
The Argentine educational system, of which Ciudad Autonoma de Buenos Aires (CABA) is 
part, faces numerous problems and produces generally poor results, both on international 
tests like Programme for International Student Assessment (PISA) and on regional 
assessments like Estudio Regional Comparativo y Explicativo (ERCE). On PISA 2022, the 
country scored 400.7 points and ranked  below Chile (448), Uruguay (430), Costa Rica 
(415), Mexico (415), and Brazil (410). PISA data shows that 54.4% of students in Argentina 
do not reach the minimum performance level established by the Organization for Economic 
Co-operation and Development (OECD). Rather, only 5 out of 10 students achieve the 
most basic reading level; and only 1% of students in Argentina achieve the highest levels of 
reading performance for their age (5 and 6). The regional ERCE 2019 test, which classifies 
students into four levels, showed that 46% of third-grade students in Argentina are at the 
lowest level (Level I). This means they are unable to locate information in text, or make 
simple inferences from age-appropriate texts. Only 14% of Buenos Aires students reached 
Level IV, which indicates the highest performance level in reading.  
Literacy results are poor throughout the system, whether in public or private schools. Many 
families tend to move children into the private system in an attempt to ensure more class 
days. In private schools, there is more predictability, to some extent, as private schools do 
not grapple with closures due to labor strikes or infrastructural issues. In the public system, 
the level of absenteeism for both students and teachers is very high, adding additional 
strain to a struggling system and further decreasing opportunities for literacy learning in the 
early primary grades. The public education system at national and municipal levels is faced 
with structural and contextual challenges that limit the effectiveness and sustainability of 
interventions. Added to these challenges is a certain ‘normalization’ of absenteeism; this 
attitude shapes a school culture where attendance is not always considered a priority 
value. 
Until 2025, the early literacy instruction method adopted by CABA was a whole language, 
balanced approach to early literacy, with no letter-sound instruction nor reading aloud in 
class. A key element of this approach is the belief that literacy development occurs fostered 
by exposure to reading and print, by participating and being immersed in environments with 
books and written words, and by teachers reading to their students. In such an 
environment, children are supposed to develop the ability to read without direct instruction, 
as they "construct" this knowledge on their own.  
 
Although Spanish has a transparent orthography, structured literacy instruction remains 
essential, as transparency does not eliminate all reading acquisition challenges. The 
development of select reading skills (e.g., fluency measures) in opaque orthographies, like 
English and French, have been shown to take somewhat longer when compared with more 
transparent orthographies, like Spanish (Caravolas et al., 2012, 2013). Similar skills and 
knowledge, however, underpin reading development in opaque and transparent writing 
systems, as reviewed above.  
6 

 
Pilot work preceding the current research 
 
Before the present investigation, a pilot project was conducted in Buenos Aires schools 
(Braze, Salvarezza, & Pugh, 2020). Six first grade classrooms and six control classrooms 
participated, enlisting a total of 328 children. Teachers received PD training and taught the 
structured literacy program, Aprendo Leyendo (AL), in their classrooms. AL is designed for 
early Spanish-speaking readers and provides systematic phonics-based instruction in 
decoding and spelling, as well as instruction in reading comprehension strategies, syntax, 
morphology, vocabulary, and handwriting (see details in Methods). Although intended for 
full year instruction, the amount of instruction received by participants fell far short of 
expectations due to high rates of student absenteeism, frequent school closings, and lack 
of uptake from classroom teachers. As a result, while children in the structured literacy 
classrooms demonstrated a significant advantage in sentence reading comprehension at 
the end of the year, other outcomes were equivalent for the two conditions. This work also 
revealed that almost all children entered first grade insufficiently prepared for early reading 
instruction. Findings also indicated the need for more comprehensive PD and close 
attention to teacher PD response and the fidelity with which teachers implemented the AL 
program. Finally, the researchers noted the systemic barriers that resulted in the high rates 
of absenteeism across all 12 classrooms. 
 
What predicts individual differences among children in reading development? 
Because there are large differences among children in any classroom, there have been 
many attempts to identify predictors of their varying trajectories and of their different 
responses to instruction and intervention. Different sets of cognitive, behavioral, and 
reading-related predictors have been examined for their ability to predict individual 
differences in reading outcomes. Phoneme awareness, letter–sound knowledge, and rapid 
automatized naming have been shown to predict reading development across languages. 
Recently, Siegelman and colleagues (2021) characterizes additional predictors of individual 
reading gains from children’s differential reliance on psycholinguistic properties, reflecting 
the functional organization of their reading system (i.e., integrity of print-speech and 
print-meaning pathways). . 
Another promising predictor of individual differences has been revealed with use of an 
experimental task rather than a standardized test. Set for Variability (SfV) (Gibson & Levin, 
1975; Venezky, 1999) is typically defined as a learner’s ability to correct a mispronunciation 
of an unfamiliar word to its actual spoken word form. In English and other “opaque” 
orthographies, SfV is typically tested in a spoken language task where participants are 
presented in each trial with a decoded phonological form of a word (e.g., /brɪkfast/) and are 
asked to guess the correct intended word (e.g., /brɛkfast/). Recently, studies have shown 
that SfV performance correlates highly with reading proficiency among early readers of 
English (e.g., Steacy et al., 2019) even dominating other more canonical predictors such as 
phonological awareness (e.g., Steacy et al., 2023). These high correlations have been 
interpreted as suggesting that the ability to arrive at a correct (i.e., lexical) form of a word 
from a mispronounced decoded spoken form taps into multiple important skills, including 
7 

the integrity of the phonological system, vocabulary knowledge, and print-speech and 
speech-print relations (see Edwards et al., 2022). 
Spanish has a transparent orthography and thus does not allow the creation of decoded 
spoken word forms as stimuli. In the current study, we therefore designed a new SfV 
Spanish task, which is meant to tap into the integrity of the phonological system without 
needing decoded stimuli. In particular, we used as stimuli spoken pseudowords that are 
close in phonological space to actual words (e.g., /amimal/). Then, similarly to the English 
SfV task, participants were instructed to guess the intended correct spoken form of the 
word (e.g., /animal/). With this task at hand, we could then examine whether SfV predicts 
reading proficiency outcomes even in a transparent orthography. If so, this would suggest 
that one’s ability to correct mispronounced spoken words to arrive at lexical forms is 
important regardless of the transparency of their writing system (i.e., even when a writing 
system does not evoke decoded forms).  
Research Questions 
The overarching goal of the present study was to carry out a longitudinal observation of the 
effects of an evidence-based teacher training program (see below for details)  and 
corresponding teacher and student instructional materials on foundational literacy 
outcomes. We conducted four assessments of literacy and literacy-related skills over the 
span of two years in schools in the province of Buenos Aires, Argentina. We evaluated the 
early reading skills of children whose teachers were trained in the program and had 
Aprendo Leyendo’s instructional materials, and compared their performance and evolution 
with the skills of children whose teachers were not trained in the program and did not have 
the instructional materials. In addition, individual differences in the children’s reading growth 
were assessed with a limited set of predictors.  
There are three questions on which the current research is based. 
1. Is a two-year evidence-based teacher training program in Spanish-language 
structured literacy instruction feasible to implement in Buenos Aires schools and 
acceptable to participating teachers? This question was assessed using 
descriptive/qualitative survey data collected from participating teachers. 
2. Does a two-year evidence-based teacher training program in Spanish-language 
structured literacy instruction produce gains in reading development for Grade 1 and 
2 children relative to their peers in control schools? This issue represents the 
primary question motivating the research, and it was evaluated using linear 
mixed-effect models examining performance differences in the teacher training vs. 
control groups on multiple reading and reading-related outcomes over time.  
3. Do individual differences in reading and reading-related skills at entry predict 
differential reading gains among the children receiving Spanish-language structured 
literacy instruction? Separate linear mixed-effects models for each potential predictor 
variable and each outcome were developed to determine whether a variable was 
associated with reading growth and with better outcomes in the teacher training or 
the control groups.  
 
8 

Methods 
Context for the research 
To undertake the present research, an agreement was entered into with the CABA Ministry 
of Education and the University (Universidad de la Ciudad de Buenos Aires). The Ministry 
alone selected the participating schools and allocated them to intervention or control 
groups. Their school selection was guided by the following considerations: 
1. That various districts were represented, which in turn represent different 
demographic groups. 
2. That in each district, there was one intervention school and one control school. 
3. That the district supervisors did not oppose the research. 
 
The research team was not permitted to participate in school selection or allocation of 
schools to groups. This constraint prevented the investigators from undertaking randomized 
assignment of schools to intervention or control conditions. During the research project, 
high levels of student absenteeism influenced the continuity of classroom work and the 
evaluations conducted at four different times. As an external research group, direct access 
to school attendance records was not permitted by the Ministry, thus accurate data on 
absenteeism cannot be reported here. 
 
At the beginning of the project, demographic data for both intervention and control schools 
was requested from the Ministry of Education's Statistics and Census unit. The data 
provided were limited and incomplete, with information only for some families and only at 
certain data points. The schools belonged to Districts 10, 16, 18, and 21 in the City of 
Buenos Aires. In each district, the intervention school had its control counterpart. The 
different districts of Buenos Aires are located in the north, center and south of Buenos 
Aires city, and the levels of household income vary between them. Families can send their 
children to any school regardless of where they live, so they tend to choose a school in 
better neighbourhoods on the belief that those are better. 
 
In an effort to obtain more demographic data, a survey was distributed to the families of 
participating students to complement the demographic data provided by the Ministry. 
Argentina has a system of conditional cash transfers, Universal Child Allowance (AUH), 
aimed at low-income families. This benefit, which reaches approximately 20% of the 
country's minors, requires schooling and compliance with children's vaccination schedules. 
 
There were 431 parents (in control and intervention group) who responded to the survey 
(out of 1050 people receiving the survey). Overall, 44% responded to the survey. Only 67 
families stated they received the AUH, a state financial aid, and 16 of them also received 
some public transport benefit. Only 19 parents in total stated they had completed tertiary 
education, and 4 parents had incomplete primary education. The vast majority of parents 
stated they had Wi-Fi or broadband internet at home, as well as cell phones; furthermore, a 
high percentage responded that they had a computer and/or tablet. Although the country 
has implemented device distribution programs (such as the Conectar Igualdad plan), it has 
had a discontinuous coverage and an unequal impact in different regions of the country. 
9 

This project received an ethics review from Universidad de la Ciudad de Buenos Aires. The 
selected schools collected parental consent. 
 
Participant sample 
The Buenos Aires literacy intervention project began in the 2022 school year (school year 
starts in March and ends the first week in December). A total of 15 schools were identified to 
participate, 7 in the control group and 8 in the intervention group. The total sample of students 
was 537: 258 children participated in the intervention group (Aprendo Leyendo), and 279 in 
the control group. All children were native Spanish speakers and were entering Grades 1 in 
2022 at the beginning of data collection (T1). Students were tracked for two years, through the 
end of their second grade. Aprendo Leyendo (AL) was taught in Grade 1 (2022) and Grade 2 
(2023) in the intervention schools, and control schools used their traditional methods of 
reading instruction 
In the two years of the project, 22 teachers (15 teachers in 2022 and 7 new teachers in 2023) 
from the intervention schools were each provided over 20 hours of PD in Aprendo Leyendo, a 
Spanish-language structured literacy program. All the teachers who participated in the training 
sessions, as they were teachers of the intervention group, completed tertiary level education.  
The Spanish-language structured literacy program—Aprendo Leyendo 
  Aprendo Leyendo (AL) is a Spanish-language multisensory structured reading program, 
designed for children in the early stages of reading development. Using an explicit, 
sequential, and multisensory approach, AL is designed to help beginning readers achieve 
automatic accurate decoding and fluent reading of connected text. AL also includes 
systematic instruction in reading comprehension strategies, syntax, morphology, vocabulary, 
spelling and handwriting. 
Throughout an instructional sequence of 96 Pasos (levels), AL teaches a range of 
comprehensive literacy content, including: phonemic awareness; letters/graphemes and 
their grapheme–phoneme correspondences; blending phonemes to read syllables, words, 
phrases, and the reading of connected text. Further, there are lessons in handwriting, 
spelling, 
grammar 
(including 
verb 
conjugations, 
pronouns, 
and 
noun/adjective 
correspondences, synonyms and antonyms), syntax, morphology, and instruction in reading 
comprehension strategies. 
All these vital components of reading are taught simultaneously in cohesive structured 
lessons, each subject reinforcing and strengthening the others. An Aprendo Leyendo lesson 
should be delivered daily and last 45-60 minutes. Each lesson has 5 components: 
1. Review (3 minutes) Review previously taught sounds using the Review Pack. 
2. Introduction of New Material (15 minutes): New material could be a phonogram, 
morpheme, or a grammatical rule. While the alphabetic code is being taught, this 
part of the lesson includes phonemic awareness and handwriting instruction.  
3. Spelling Dictation (10 minutes) Give a dictation with the new phonogram, using 
10 

words and a sentence provided in the Teacher Handbook. 
4. Reading (20/25 minutes). Read a list of words, phrases, and sentences with 
children from the Skills Books to develop decoding skills, word recognition, and 
reading fluency. Reading a decodable and controlled chapter book with children to 
develop fluency and model comprehension strategies while reading connected 
text. This portion of the lesson is also an opportunity to develop oral language as 
the conversation should not be controlled.  
5. Reinforcement. Provide reinforcement activities including reading comprehension, 
morphology, syntax, and grammar. 
For more detail, please refer to the Curriculum Overview, Instructional Sequence, and digital 
samples of the materials provided in the supplementary materials. 
Aprendo Leyendo’s integrated PD for teachers is a crucial design feature of the program as 
it provides teachers with the tools and knowledge they need to help children develop into 
independent and competent readers. The PD curriculum included 20 hours of in-person 
training in year one, 20 hours of continued ongoing support throughout both school years, 
along with the provision of print and online teacher and student materials. 
Teachers in the control schools received no special training, nor the Aprendo Leyendo 
instructional materials, and their students therefore received business-as-usual reading 
instruction. These classes served as a comparison group against which to evaluate the 
effectiveness of the AL program implemented in the intervention schools. A key element of 
the business-as-usual approach at the time is the belief that literacy development occurs 
fostered by exposure to reading and print, by participating and being immersed in 
environments with books and written words, and by teachers reading to their students. In 
such an environment, children are supposed to develop the ability to read without direct 
instruction, as they "construct" this knowledge on their own. 
Teacher Professional Development 
PD sessions for the teachers were held in 2022 (April, June, September, December 
in-person; May by Zoom) and in 2023 (in-person reinforcement in February, virtual in March). 
Due to a 50% teacher turnover in the second year of implementation, an additional in-person 
training was held in April 2023 for new teachers; these teachers therefore received half the 
training of  those who participated for both years. 
An open communication channel was established with teachers in the intervention group 
through a series of WhatsApp groups, maintained throughout the two years of the program. 
Additionally, several visits were made to model Aprendo Leyendo classes, with teachers 
observing a trainer and taking notes to apply it in their own classes and improve their work 
with the program. These visits were carried out at least three times during each year of the 
two-year project: in 2022 (June, August-September, late October approximately) and in 2023 
(April, June-August, October). 
11 

  In each visit to the intervention schools, a descriptive record was kept of how the students 
worked, how the teachers presented themselves in relation to the program, and what 
questions they had for the trainer. The instructional level the students were on was also 
recorded, and any other detail that caught attention of the trainer or needed to be highlighted. 
 
‘Business as Usual’ Teaching in CABA 
The general approach to reading instruction in CABA could be characterized as a "global/ 
whole language" or "balanced" approach. A key element of the global approach is that 
literacy development occurs fostered by exposure to reading and print, by participating and 
being immersed in environments with books and written words, and by teachers reading to 
their students. In such an environment, children are supposed to develop the ability to read 
without direct instruction, as they "construct" this knowledge on their own. This approach is 
based on the idea that learning to read and write is as natural as early language 
acquisition. Explicit teaching of decoding and reading is considered unnecessary as it is 
boring and interferes with a process the child must undertake. When the global approach 
introduces phonological awareness work, it is called a balanced or integral approach. It is 
important to note that the addition of phonological awareness does not imply that 
instruction becomes explicit and structured, as reading acquisition is still considered a 
process of construction by the student, rather than a skill taught by the teacher. 
Control teachers and classroom observations 
Teachers in the control schools did not receive AL training, and their students received the 
reading instruction typically conducted in CABA. To document these practices, the research 
team visited the control schools to observe a language class and to record the instructional 
practices using a class observation rubric. The observation rubric for control classes 
contained items related to teaching letters, reading and writing practices in class, 
vocabulary work, and practices related to phonological awareness. Less than 50% of 
Language Arts classes were found to be working on these skills. 
The team observed that, in most of the classes, the teacher read aloud, and in very few 
cases, students read on their own. Only some teachers asked questions about the text that 
they read. 90% of control group classrooms had alphabet and word charts as part of the 
classroom decoration, and a large proportion of teachers worked with upper-case print on 
the board, in some cases alternating between upper-case and lower-case. 
The observers noted that most teachers corrected writing assignments. An important 
aspect noted in control group schools was the lack of homogeneity in routines and work 
methods related to literacy. There appeared to be no uniform method or way of working 
among classrooms. 
Teaching Materials: 
Aprendo Leyendo distributed 3260 individual materials to work with the AL class groups. 
These included 1620 student skillsbooks, 1620 decodable and controlled chapter books, 
and 20 teacher sets (teacher manuals, teacher editions to the chapter books, and alphabet 
and review card packs). 
12 

Teacher Surveys: 
At the end of each school year in the study, the research team conducted a survey with 
teachers about the program and their experiences with its implementation. Out of a total of 
22 participating teachers during both years, 15 out of 15  completed the questionnaire in 
2022 and 11 out of 14, in 2023. The survey consisted of 38 items.  
The survey was administered at the end of the first year, in December 2022, and then again 
at the end of the second year, December 2023. Information was collected on teachers' 
professional trajectories, the use of reading science practices in teaching, opinions 
regarding the Aprendo Leyendo training program, the implementation of the AL program in 
their classrooms, and students' reading results and motivation. 
Measures of Reading and Reading-related Skills 
Student performance data were collected at four time points: T1 (pre-intervention), T2 
(post-year-1 intervention), T3 (pre-year-2 intervention), and T4 (post-year-2 intervention). 
Due to the Argentinian school schedule, no school classes were held between T2 and T3 
thus any change during that period reflected either continued growth or loss of skills over 
the holiday period. 
To evaluate early literacy development in Spanish, two primary assessments were 
administered: Indicadores Dinámicos del Éxito en la Lectura (IDEL; Baker et al., 2007) and 
the Tejas LEE (Texas Education Agency, 2010). These assessments were administered 
across four time points (T1–T4), depending on the subtest. Student assessment was 
carried out by two teams of graduate student examiners from the Universidad de la Ciudad 
de Buenos Aires. Examiners were trained and supervised by university faculty under the 
direction of Professor F. Salvarezza. Assessments were conducted in the students’ own 
schools. 
IDEL Subtests. IDEL is a reliable and valid (Nelson, 2001; Watson; 2004) formative 
assessment designed to measure foundational literacy skills among Spanish-speaking 
emergent readers. The following IDEL subtests were used at multiple time points: 
● Letter Naming Fluency (idel_fnl): Students named as many randomly ordered 
upper- and lower-case letters as possible within one minute (this measure was 
collected in all time points: T1–T4). The test’s score is the number of letter names 
that 
can 
be 
produced 
correctly 
in 
1 
minute 
(appearing 
below 
as 
idel_letter_naming_fluency). Note that standard practice for this test is to use mixed 
case materials. We deviated from that practice and used all uppercase materials. In 
Argentina, most printed material for beginning readers is written using uppercase 
letters only. 
● Phoneme Segmentation Fluency (idel_fsf_tlp): Students orally segmented 
individual phonemes from orally presented words of one to three syllables. Two 
scoring rubrics provide separate scores for the task, one based on phonemes 
(Phoneme Segmentation Fluency) and another based on syllables (idel_fsf_sil). 
Scores from this task are available in T1–T4. 
13 

● Nonsense Word Correct Fluency (idel_Nonsense Word Correct Fluency): 
measures fluency in nonsense word reading. Two scoring rubrics provide scores for 
number of letter-sounds correct per minute (idel_fps_tsl) and number of (non)words 
pronounced correctly (idel_Nonsense Word Correct Fluency). Students read aloud a 
list of pseudowords (e.g., ro, lali, sepi), measuring their ability to apply letter-sound 
correspondences and blend them into whole words (available in T1–T4). 
● Oral Reading Fluency (idel_flo): This subtest assessed accurate and fluent oral 
reading of a connected passage within one minute (T2–T4). 
 
Tejas LEE Subtests. The Tejas LEE is a researcher-developed assessment of Spanish 
reading skills for students in grades K–3. Based on project access, these subtests were 
administered primarily at T4 and serve as an independent outcome evaluation. The Tejas 
Lee included the following components: 
● Words Read Correctly Per Minute: A composite score combining accuracy and 
fluency in reading grade-level word lists (conducted in T3–T4). 
● Passage Fluency (lectura_fluidez): Students read connected text aloud for one 
minute, measuring word reading fluency (conducted in T4 only). 
● Passage Comprehension (lectura_compr): After reading a text aloud, students 
answered eight comprehension questions targeting both explicit and implicit 
information (T4 only). 
● Dictation (l_dictado): Students wrote ten dictated words of varying complexity, 
presented in isolation and within a sentence context to avoid homophone confusion 
(T4). 
● Letter Sound (letter_sound): Students named the corresponding sound for each of 
30 randomly ordered upper- and lower-case letters (T2–T4). 
 
Rapid Automatic Naming (RAN). A Rapid Automatic Naming (RAN) test assesses the 
speed and accuracy with which an individual can orally identify a series of familiar stimuli, 
such as common colors and everyday items, presented in a randomized, repeated 
sequence. This timed measure evaluates automaticity in lexical retrieval, a skill closely 
linked to reading fluency and efficiency. This test was administered at T1 only. 
Nonword repetition. A Nonword Repetition task assesses phonological working memory 
by requiring individuals to repeat unfamiliar, phonotactically plausible sequences of sounds 
that do not form real words. Performance on this task reflects the capacity to temporarily 
store and reproduce novel phonological information, a skill linked to language development 
and reading acquisition.This test was administered at T1 and T4. 
Peabody Picture Vocabulary Test. The Peabody Picture Vocabulary Test measures an 
individual’s ability to comprehend spoken words by having them select, from a set of four 
pictures, the image that best represents the meaning of each word presented orally by the 
examiner. This test was administered at T1 only. 
14 

Set for Variability. The Set for Variability task measures an individual's ability to correctly 
identify a mispronounced or phonologically altered version of a word and match it to the 
correct lexical form (e.g, amimal x  animal; torduga x  tortuga) This task assesses flexible 
word recognition processes that support decoding irregular or less familiar words. This test 
was administered at T1 and T4. 
 
Results 
Feasibility and acceptability results 
The first research question addressed whether a two-year evidence-based teacher training 
program in Spanish-language structured literacy instruction was feasible to implement in 
Buenos Aires schools and acceptable to participating teachers. This question was 
assessed using descriptive/qualitative survey data collected from participating teachers.  
No formal analyses of these descriptive data were undertaken but an overview of teacher 
responses is summarized below. 
Overall, participating teachers reported very favorable opinions about the simplicity and 
feasibility of implementing the program in the classroom and its efficacy with students. The 
survey results revealed that: 
● 100% of teachers agreed that they would recommend the training course to their 
colleagues. 
● 94% of them believe that their students are learning to read better than in previous 
years. 
● 100% believe that their students improved their reading comprehension skills 
compared to previous years. 
● 94% of respondents believe that their students were more motivated to learn than in 
previous years. 
● 100% of respondents believe that the methodology helps them improve other 
learning areas. 
These descriptive data support the conclusion that the PD Program and the associated AL 
instructional materials were not only feasible to implement in a variety of classrooms, but 
teachers felt very positive about their students’ response to the program and their own 
ability to foster reading development in these children. 
Main Analyses of Results 
The main analyses focused primarily on comparing gains in reading measures in the 
intervention versus the control group. First, to make sure any differences in gains were not 
related to pre-existing differences between the two groups, we examined whether there are 
any differences at Time 1 (T1) between the control and intervention groups. We established 
the groups had comparable T1 reading skills, with the exception of some marginal 
15 

differences, which, if anything, favor the control group (see analyses of T1, below). Second, 
We examined group-level differences in reading measures between groups over time. We 
did so by running statistical models that estimate whether there is a main effect of group 
(across timepoints, i.e., evidence for a general advantage for one group over the other 
across timepoints tested) and an interaction effect between group and time (i.e., evidence 
for differential growth between the groups). Third, we examined whether individual 
differences in component skills of reading collected at T1 predicted reading gains, and 
whether there are component skills that are differentially predictive of skill in one group 
versus the other. To this aim, we ran statistical models examining whether T1 individual 
differences measures interact with group and time to predict reading outcomes.  
We note that in the Results section, we review in the text (and in accompanying Figures) all 
significant (p < .05) and marginally significant (p < .1) effects. The rationale in reporting 
marginal effects as well was both to provide a fuller picture of the findings, and, given the 
large number of comparisons involved (i.e., multiple dependent variables), to get estimates 
of the proportion of findings that show both significant and marginal significant effects 
(recall that under the null hypothesis, p-values are uniformly distributed, hence the 
expected proportion of significant findings is 1/20, and marginal findings is 2/20).  
Baseline Differences in Reading Skill Dependent Variables at T1 
Two assessments of reading skills were measured in T1: Letter Naming Fluency and 
Nonword Fluency. As can be seen in Table 1, there was a marginally significant difference 
between groups in the Letter Naming Fluency task (t(367)=1.83, p=0.069, d=0.19). 
However, this difference had to do with the control group numerically outperforming the 
intervention group (with a smaller numeric difference in the same direction also in nonword 
reading, see Table 1). Such baseline differences means that the reported advantages of the 
intervention group reported below are observed despite a slight numeric disadvantage at 
T1. 
Table 1 further presents baseline differences in component skills of reading collected at T1 
(i.e., set for variability, vocabulary, RAN, phonological awareness (segmentation), and 
nonword repetition). As can be seen, there were no significant differences between the 
control and intervention group in these tests. There was again a marginal difference in 
phonological awareness (t(366)=1.69, p=0.092, d=0.18), of the same trend, with the control 
group showing numerically better performance. The control group showed similar numeric 
(statistically insignificant) trends in several other measures (Table 1).  
 
16 

 
 
Group-Level Intervention Effects  
Next, we tested group-level differences between the two groups over time. For reading 
outcomes that were collected at more than one time point, we used linear mixed-effect 
models, with fixed effects for group (effect-coded, control coded as (-1)), time (inserted as 
an effect-coded categorical variable, T1 coded as (-1)), and their interaction. Models also 
had by-participant random intercepts, which was the maximal random-effect structure 
justified by the design that converged (Barr et al., 2013; a model with additional random 
slopes for time was not identifiable given the number of parameters to be estimated and the 
number of data points). Models here and below were implemented in R, using the lme4 
package (Bates et al., 2015), with significance of fixed effects estimated using the lmerTest 
package (Kuznetsova et al., 2017). Because we were interested in the overall effects of 
time, group, and their interaction, rather than specific time point comparisons, we report F 
tests for the full terms (using the anova() function in R). Effect sizes were estimated using 
the effectsize package (Ben-Shachar et al., 2020). Estimated effects over time are then 
visually depicted for significant and marginally significant effects (plots generated using the 
interactions package, Long, 2024). F-values and significance levels for the effects of group, 
time, and their interaction are presented in Table 2. For the three measures that were 
assessed only at T4 (Text Reading Fluency, Text Reading Comprehension, and Dictation), 
we conducted t-tests to examine the difference between the two groups. The results of 
these comparisons are presented in Table 3. 
As expected, in all dependent variables with more than one assessment, there was a 
significant main effect of time (see Table 2), meaning that, on average, participants 
17 

improved their reading with time. Importantly, several models also revealed greater 
improvement in the intervention than the control group (a significant main effect of group). 
Thus, students in the intervention group had significantly better performance in text reading 
comprehension, measured at T4 (t(386)=2.27, p=.024, d=.23; Fig. 1A), and in letter-sound 
naming, measured at T2-T4 (F(1, 425.4)=18.53, p<.001, η²p=.04; Fig.1B), alongside 
marginally significant better performance in text reading fluency (i.e., number of correctly 
read words per minute in a text), measured at T4 (t(302)=1.69, p=.092, d=0.19; Fig. 1C), 
and in sentence comprehension, measured at T2-T4 (F(1, 422.8)=3.61, p=.058, η²p=.008; 
Fig. 1D).  
In addition, other reading measures showed greater improvement in the intervention group 
through time, as evidenced by significant group-by-time interactions. Thus, students in the 
intervention group also showed significantly greater gains in letter naming fluency, 
measured at T1-T4 (F(3, 1132.1)=3.8, p=.01, η²p=.01; Fig. 2A), in oral word reading 
fluency, measured at T2-T4 (F(2, 748.1)=3.15, p=.043, η²p=.008; Fig. 2B), and in word list 
reading fluency (i.e., number of correctly read words per minute in a word list), measured at 
T3-T4 (F(1, 276.6)=6.68, p=.009, η²p=.02; Fig. 2C). Overall, then, in 7 out of 10 dependent 
variables, there was significant or marginally significant statistical evidence for either an 
overall advantage for the intervention group over the control group, for a better growth in 
the intervention group through the timepoints measured, or both.  
 
18 

 
 
 
 
 
19 

Figure 1. Estimated Effect of Group on Text Reading Comprehension (Top Left Panel, A); 
Estimated Interaction Effect of Group and Time on Letter-Sound Naming (Top Right Panel, 
B); Estimated Effect of Group on Text Reading Fluency (Bottom Left Panel, C); and 
Estimated Interaction Effect of Group and Time on Sentence Comprehension (Bottom Right 
Panel, D). 
 
Notes: †<.1; * <.05; **<.01; ***<.001 
 
20 

Figure 2. Estimated Interaction Effect of Group and Time on Letter Naming Fluency (Top 
Left Panel, A); Estimated Interaction Effect of Group and Time on Oral Word Reading 
Fluency (Top Right Panel, B); and Estimated Interaction Effect of Group and Time on Word 
List Reading Fluency (Bottom Panel, C). 
 
Notes: †<.1; * <.05; **<.01; ***<.001 
 
Individual Differences in Component Skills as Predictors of Reading Gains  
Lastly, we tested whether individual differences in component skills of reading measured at 
T1 differentially predicted performance and gains over time in the two groups. Again, for 
reading outcomes that were collected at more than one time point, we used linear 
mixed-effect models, with fixed effects for group (effect-coded as above), time (effect-coded 
21 

as above), the component skills (scaled and centered), all their two-way interactions, and 
their three-way interaction. We ran separate models with each component skill of reading 
as a predictor, for each dependent variable. The only exception was the two sub-scales of 
Rapid Automatized Naming (colors and objects) which were highly correlated (r = .56) and 
thus replaced by a composite score (i.e., average of Z-scores of the two sub-scales). 
Models also again had by-participant random intercepts. For simplicity and given the large 
number of models tested, we report the F-values for the two interactions of interest (i.e., 
those that involve Group): Component Skill by Group, and Component Skill by Group by 
Time (see Table 4), which reflect differential performance or growth in the two groups 
depending on the baseline component skill level. For the three measures that were 
assessed only at T4 (i.e., Text reading fluency, Text Reading Comprehension, and 
Dictation), we conducted a linear model with fixed effects for group (effect-coded, same as 
above), the component skill (scaled and centered), and their interaction. For brevity we 
report for these models the estimated effect of the interaction (Table 5).  
While not all component skills and/or outcomes showed significant interaction effects 
involving Group (see Tables 4 and 5), some specific component skills and reading 
outcomes did yield significant or marginally significant interactions. In particular, we found 
that students with higher scores in the phoneme segmentation task, measured at T1, had 
significantly higher scores in the intervention than the control group in text reading 
comprehension, measured at T4 (F(1, 329)=3.98, p=.047, η²p=.01; Fig. 3A). Higher T1 
scores in phoneme segmentation were marginally associated with better performance in 
the intervention than the control group (i.e., Group by Phoneme Segmentation interaction) 
in letter naming, measured in T1-T4 (F(1, 364.4)=3.21, p=.074, η²p=.009; Fig. 3B), nonword 
naming, measured in T1-T4 (F(1, 367)=3.13, p=.078, η²p=.008; Fig. 3C), and oral word 
reading fluency, measured in T2-T4 (F(1, 362.8)=3.69, p=.056, η²p=.01; Fig. 3D). 
Set for Variability scores at T1 interacted significantly with Group to predict oral word 
reading fluency, measured in T2-T4 (F(1, 357.4)=4.03, p=.045, η²p=.01), word list reading 
fluency, measured in T3-T4 (F(1, 318.2)=4.65, p=.032, η²p=.01), and text reading 
comprehension, measured in T4 (F(1, 324)=7.25, p=.007, η²p=.02). In all these cases, 
students with higher Set for Variability T1 scores had better reading skills in the intervention 
vs. control group (see Figures 4A-4C). Lastly, T1 vocabulary scores, T1 scores in the Set 
for Variability task, and T1 nonword repetition scores, showed significant three-way 
interactions with Group and Time, such that students with higher baseline scores in these 
component skills had better gains in the intervention group than the control group in word 
list reading fluency, measured in T3-T4 (Vocabulary: F(1, 250.8)=4.04, p=.046, η²p=.02; 
Fig. 5A; Set for Variability: F(1, 238.7)=6.63, p=.011, η²p=.03; Fig. 5B; Nonword Repetition: 
F(1, 248.5)=5.42, p=.021, η²p=.002; Fig. 5C).  
These results suggest that, together with the general advantage in reading outcomes 
associated with the intervention at the group-level, the intervention was more effective for 
22 

some children, in particular those with higher component reading skills at baseline. We 
return to these findings in the General Discussion. 
 
 
23 

 
24 

 
 
 
 
Figure 3. Estimated Interaction Effect of Group and Phoneme Segmentation at T1 on Text 
Reading Comprehension (Top Left Panel, A); Estimated Interaction Effect of Group and 
Phoneme Segmentation at T1 on Letter Naming (Top Right Panel, B); Estimated Interaction 
Effect of Group and Phoneme Segmentation at T1 on Nonword Naming (Bottom Left Panel, 
C); and Estimated Interaction Effect of Group and Phoneme Segmentation at T1 on Oral 
Word Reading Fluency (Bottom Right Panel, D). 
25 

 
Notes: †<.1; * <.05; **<.01; ***<.001 
 
 
26 

Figure 4. Estimated Interaction Effect of Group and Set for Variability at T1 on Oral Word 
Reading Fluency (Top Left Panel, A); Estimated Interaction Effect of Group and Set for 
Variability at T1 on Word List Reading Fluency (Top Right Panel, B); Estimated Interaction 
Effect of Group and Set for Variability in T1 on Text Reading Comprehension (Bottom 
Panel, C). 
 
Notes: †<.1; * <.05; **<.01; ***<.001 
 
 
27 

Figure 5. Estimated Interaction Effect of Group and Vocabulary size in T1 on Word List 
Reading Fluency over time (Top Panel, A); Estimated Interaction Effect of Group and Set 
for Variability in T1 on Word List Reading Fluency over time (Middle Panel, B); Estimated 
Interaction Effect of Group and Nonword Repetition in T1 on Word List Reading Fluency 
over time (Bottom Panel, C). 
 
Notes: †<.1; * <.05; **<.01; ***<.001 
 
28 

 
 
 
Discussion 
The present research was designed to assess the efficacy of early structured literacy 
intervention delivered by teachers who received 40 hours of PD and additional support in 
structured literacy methods, throughout two school years. Eight Buenos Aires schools 
served as intervention schools, and seven were control schools. A Spanish structured 
literacy curriculum, Aprendo Leyendo (AL), was taught in Grades 1 and 2 in the intervention 
schools by teachers receiving PD and ongoing support. Control schools used their 
traditional methods of reading instruction, and their teachers did not receive the PD. AL is a 
Spanish-language reading program, designed for children in the early stages of reading 
development. 
Intervention students demonstrated significant post-program advantages on several 
reading and reading-related skills, with better T4 performance than controls on passage 
comprehension and letter-sound naming. Differential growth on two word reading fluency 
and one letter naming fluency measure were revealed, and significant gains on two 
component skills, phoneme segmentation and set for variability. Individual differences 
analyses showed that, generally, children with better component reading skills at Grade 1 
entry demonstrated the greatest intervention gains. Overall, the results of the study provide 
evidence that teacher training can have a significant impact on early literacy outcomes in 
complex educational environments; moreover, the impact is driven by an intervention that 
can be implemented with relative ease and timeliness, and, especially, cost-effectiveness.  
The benefits for students of well-trained, effective teachers have been well established. But 
these benefits may be especially pronounced in poorer countries with substantial social and 
economic challenges. In lower-income and lower middle-income countries, for example, 
there is significant instructional variability and the gaps in teacher preparation are 
pronounced (Dickinson, Connor, & Hadley, 2023). As regional economic challenges vary 
greatly in LAC countries, so does teacher training and access to effective and updated 
materials. Initiatives that emphasize teacher professional development have shown 
encouraging results, especially when they are aligned closely with the Science of Reading 
and include continued, systematic implementation and evaluation of outcomes.  
In a similar PD and intervention program, in Chile, Pallante and Kim (2013) evaluated the 
Collaborative Language and Literacy Instruction Project (CLLIP), a multicomponent literacy 
model that provided teachers with targeted training on foundational literacy skills 
(phonological awareness, phonics, vocabulary) and in comprehension and writing. 
Teachers received instructional materials that integrated theoretical background, practical 
29 

demonstrations, and collaborative lesson planning. An evaluation revealed significant 
improvement in student outcomes. Kindergartners in the CLLIP classrooms were better 
than their non-CLLIP peers at letter naming, word reading, vocabulary, and phonemic 
segmentation; and first-grade students, in turn, were better at vocabulary, reading fluency, 
and comprehension. These effects, ranging from small (d = .18 in kindergarteners’ word 
reading) to large (d =.70 in kindergarteners’ letter-naming fluency), demonstrated the 
potential of structured, coaching-based teacher training to accelerate early literacy growth.  
As discussed before, reliable effects of teacher training were found in interventions that 
combine evidence-based professional development with structured materials, as seen in 
Aprendamos todos a leer in Colombia (Márquez de Arboleda et al., 2020) and CLLIP in 
Chile (Pallante & Kim, 2013).  
In the present study, the teachers’ students were evaluated on a range of reading and 
reading-related skills using a Spanish reading assessment administered at four time points, 
before and after Grade 1, and before and at the end of Grade 2. The project was a 
controlled research evaluation because students’ learning trajectories on the performance 
measures were compared with those of same-grade students in control schools. The 
control students were assessed at the same time intervals on the same measures, but their 
teachers did not receive the PD training and students received reading instruction 
according to the business-as-usual model of their schools.  
Findings of the data analyses provide positive evidence of the value of the PD and 
structured literacy instruction provided to teachers and their students in the intervention 
schools. Teachers who received the PD and taught the Aprendo Leyendo program had 
students who demonstrated greater growth than their control peers on important 
dimensions of reading and reading-related skills. On two of the IDEL measures, children in 
the Intervention schools showed differential growth in letter naming fluency and in phoneme 
segmentation fluency relative to controls. The Group x Time interaction for letter naming 
fluency revealed that while the intervention students were lower performing at T1, they 
‘caught up’ and were equivalent to the control students at T4. In fact, most of this growth 
occurred during the first year of instruction (T1 to T2). For phoneme segmentation fluency, 
a similar pattern was observed. These findings are documented in the Supplementary 
Materials, in Supplementary Table S1 and Supplementary Figure S1. 
Another aspect of the present study is that participating teachers reported very favorable 
opinions about the simplicity and feasibility of implementing the program in the classroom 
and its efficacy with students. We do not provide a formal analysis of teacher surveys; 
however, 100% of teachers in the training program (i) agreed that they would recommend 
the training course to their colleagues, (ii) believed that their students improved their 
reading comprehension skills compared to previous years, and (iii) believed that the 
methodology helps them improve other learning areas. Also, 94% of the participating 
teachers believed their students were learning to read better than in previous years and 
30 

that their students were more motivated to learn than in previous years. The present study, 
thus, suggests that there were significant differences in the reading achievement of 
students whose teachers were trained with the program and, additionally, that the program 
was met with high teacher acceptance and satisfaction. These findings differ from those of 
Braze et al. (2020) who reported a lack of uptake and buy-in from classroom teachers in 
their study.  
Growth on another foundational reading skill was evaluated using the Tejas LEE 
Letter-Sound measure. The Tejas LEE is considered a better-designed Spanish-language 
reading assessment tool and only became available to the team after the project was 
underway. Because of its strengths, however, we decided to incorporate it in the 
assessments as we collected the data. The Tejas LEE Letter-Sound measure was one of 
the first included and thus was available for testing at T2, T3, and T4. At T2, the 
Intervention group was already superior to the control group and maintained this superiority 
at T3. At T4, the two groups were not significantly different. Results indicated strong 
significant Group and Time main effects, but a nonsignificant interaction. One could 
speculate that, had the measure been available at T1, we might have observed such an 
interaction. Given the scores of the intervention group at T1 on some of these measures, it 
is quite possible that their superiority at T2 and T3 may be attributable to the structured 
literacy instruction they received in Year 1. 
Two more advanced reading skills were also assessed on the Tejas LEE, although at later 
time points. Word reading fluency (words read correctly per minute) was available at T3 
and T4, and a significant Group x Time interaction was revealed. The intervention group 
performed lower than controls at T3, but was superior to them at T4. This measure of word 
reading efficiency is an important outcome, and a building block of higher-order reading 
skills. The ultimate goal of reading instruction is to help children become independent and 
competent readers, able to enjoy reading for pleasure and learning, and capable of reading 
with fluency and comprehension. Thus a key outcome included the passage 
comprehension measure on the Tejas LEE. This subtest was only available at T4 
unfortunately, but it served as an independent assessment of where the two groups placed 
in general terms at the end of the two years. The intervention group was superior to the 
control group on Tejas LEE Passage Comprehension at T4 (p < .02), with a small but 
significant advantage (Cohen’s d = .23) on this important reading outcome. 
While the conditions under which this research was undertaken were not ideal, a common 
lament for real-world evaluation studies, the results are positive and demonstrate the 
efficacy of the combined PD and structured literacy intervention provided to the intervention 
schools. Although the children in intervention schools often began at somewhat lower 
levels of skill than their control school peers, they made significant gains and demonstrated 
differential positive growth on several important outcomes of reading development. The 
31 

positive response of the teachers involved is testimony to the success of the project from 
the front lines. 
The present findings add to the sparse empirical literature on the efficacy of early education 
initiatives in the LAC. Rebecca Stone and her colleagues conducted a systematic 
evaluation of evidence (Campbell Systematic Reviews, 2020) on the effectiveness and 
fidelity of implementation of various programs implemented in the LAC region that aim to 
improve early grade learning (EGL) outcomes. A review of available quantitative evidence 
revealed that teacher training, nutrition, and technology programs were not reliably 
associated with improved early grade learning outcomes in the LAC. A narrative synthesis 
of the programs, however, did identify factors that could facilitate a positive impact from 
educational programs on EGL outcomes. One of these determinants was a combination of 
teacher training with ongoing coaching and communication from mentors, a design feature 
of the teacher training program implemented in the present study. Stone et al. (2020) 
caution that the evidence base in LAC is too small to permit strong conclusions. 
Nevertheless, they do note some evidence supporting the importance of phonological 
awareness to EGL outcomes, and they speculate that improved preschool programs could 
facilitate better outcomes in elementary grades.  
The individual differences analyses summarized in the Results section revealed that the AL 
intervention, while generally beneficial, was more effective for some children, in particular 
those children with higher component reading skills at baseline. This is an example of 
Matthew effects in reading (Stanovich, 1986, 2000), a phenomenon by which “the rich get 
richer and the poor get poorer”. Stanovich argues for greater appreciation of “reciprocally 
facilitating relationships” (Walberg et al., 1983, 1984) that may be a major cause of large 
individual differences in reading outcomes and other educational achievement data. It is 
also noteworthy that one of the predictors of reading gain was set for variability 
performance (i.e., mispronunciation correction task): A task we adapted for the purpose of 
the current study to Spanish, by creating stimuli that are close phonological neighbors to a 
target spoken word. Notably, we found that set for variability, a measure presumably 
reflecting the integrity of the phonological system (see Edwards et al., 2022; Steacy et al., 
2023), is relevant not only in opaque writing systems, where it has been mostly studied to 
date, but also in Spanish, a transparent writing system. 
The interaction between where children start and their eventual reading outcomes suggests 
an urgent need to do more on pre-reading phonological readiness and other reading 
readiness skills in preschool to facilitate maximum benefits from reading instruction in the 
early elementary grades. Recognition of the important role of early phonological awareness 
and the inherent advantage enjoyed by more skilled children at school entry leads to the 
realization that preschool programs could exert a potentially large positive influence on 
EGL outcomes. In Argentina, education is compulsory from the age of four years. From the 
present data and those reviewed by Stone et al. (2020), a comprehensive framework for 
32 

education in the preschool years could be advocated. Preschool curricula rich in oral 
language development and including instructional activities to promote phonological 
awareness, vocabulary, print awareness, and pre-reading skills could enhance the 
academic readiness of thousands of young children currently ill-prepared to begin reading 
instruction. 
Overall, these findings can inform educational administration and policy development. The 
success of the present project demonstrates the impact of structured literacy PD and 
instruction in the early grades and demonstrates that better literacy outcomes may be 
achieved with research-based structured literacy programming for all beginning readers. 
These findings support continued use and ultimate scaling of implementation for structured 
literacy initiatives to improve literacy outcomes for children across Argentina. 
Many positive program evaluation findings remain siloed in academic publications and may 
never exert an impact on actual classroom practices. In the present instance, the exact 
opposite scenario occurred. In 2024, co-author FS presented the findings to the Ministry of 
Education and other authorities in Buenos Aires. CABA had a whole language, balanced 
approach to literacy, with no letter-sound instruction nor reading aloud in class. After the 
results of this research were presented to the Ministry and other authorities, however, the 
Ministry decided that all public schools in CABA would shift from balanced to explicit 
literacy instruction, and that the curriculum and books and materials would be rewritten 
according to the evidence found in the research. From 2025 on, CABA has a structured 
and explicit literacy curriculum and materials across schools and districts. This is a 
remarkable timeline for the translation of research into meaningful classroom practice. 
 
 
 
 
 
33 

 
Supplementary material 
Group level effects on component skills 
Similar to the group-level analysis of the group and time effects on reading skills, we 
analyzed the group and time effects on component skills that were collected at more than 
one time point. In this analysis, we used linear mixed-effect models, with fixed effects for 
group (effect-coded, control coded as (-1)), time (inserted as an effect-coded categorical 
variable, T1 coded as (-1)), and their interaction. Models also had by-participant random 
intercepts, which was the maximal random-effect structure justified by the design. F-values 
and significance levels for the effects of group, time, and their interaction are presented in 
Table S1. The three measures that were assessed in more than one time point were 
Phoneme Segmentation, Set for variability, and Nonword Repetition. For all the component 
skills with more than one assessment, there was a significant main effect of time (see Table 
S1), meaning that, on average, participants improved in their component skills with time. 
Two models also revealed greater improvement in the intervention through time compared 
to the control group, as evidenced by significant group-by-time interactions. Thus, students 
in the intervention group showed significantly greater gains in phoneme segmentation, 
measured at T1-T4 (F(3, 1140.94)=2.97, p=.031, η²p<.01; Fig. S1A), and in Set for 
Variability, measured at T1 and T4 (F(1, 385.59)= 5.71, p=.017, η²p=.01; Fig. S1B) 
 
Figure S1. Estimated Interaction Effect of Group and Time on Phoneme Segmentation 
(Left Panel, A); and Estimated Interaction Effect of Group and Time on Set For Variability 
(Right Panel, B). 
34 

 
Notes: †<.1; * <.05; **<.01; ***<.001 
 
35 

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