Authors

Beth A. Morton

Education Statistics Services 

Institute–American Insitutes for 

Research

Ben Dalton

Formerly of the Education 

Statistics Services Institute– 

American Insitutes for Research

For more information about 

the Stats in Brief series, contact 

Kathryn Chandler, National 

Center for Education Statistics, 

(202) 502-7486

May 2007

Changes in Instructional Hours in Four Subjects by 

Public School Teachers of Grades 1 Through 4 

Stats

in Brief

Introduction

There has long been an interest in the use of school time as a means of increasing student 

achievement. Prior research has focused on the amount of time allocated to instruction and 

how that time is used (e.g., Berliner 1990; Carroll 1963). Findings support the belief that 

differences in school and instructional time are related to the amount of curriculum teachers 

cover and the likelihood of engaging their students in appropriately challenging material, both 

of which have been linked to student achievement (Berliner 1990; Coates 2003; Dreeben and 

Gamoran 1986).

Policymakers have also taken a strong interest in the amount and use of school time. In 1983, 

the National Commission on Excellence in Education published A Nation at Risk. The report 

called for major reforms in the American educational system including adding more time to 

the school day and school year, along with a primary focus on basic subject matter instruction—English, mathematics, science, social science, and computer science, as well as the arts 

and foreign languages (National Commission on Excellence in Education 1983).

While the Schools and Staffi ng Survey (SASS) cannot tell us how much instruction students 

receive in different subject areas, data from the SASS teacher questionnaires do allow us 

to examine how much time teachers of self-contained classrooms spend teaching certain 

subjects.1 Findings from this report show that combined teacher instructional hours in fi rstthrough fourth-grade English, mathematics, social studies, and science increased between 

the 1987–88 and 2003–04 school years. This was due to individual increases in English and 

mathematics instruction. Over the same time period, instruction in science and social science 

saw an overall decrease. 

Data and Purpose

This report describes specifi c changes in teacher instructional time from 1987–88 through 

2003–04. Analyses of these changes are possible because a subset of the teachers who completed the SASS Teacher Questionnaire were asked to report the number of hours per week 

they spent delivering instruction in four subjects—English (including reading and language 

arts), mathematics (and arithmetic), social studies (including history), and science—in all fi ve 

SASS administrations (school years 1987–88, 1990–91, 1993–94, 1999–2000, and 2003–04). 

Additionally, in 1987–88 and 2003–04, teachers were asked to report the total number of 

hours per week they spent delivering instruction in all subjects. While examining changes in 

the number of hours spent on instruction is important, the length of the student school week 

is included in the analyses so that changes in teacher instructional time can be measured in 

relation to changes in the length of the student school week. The length of the student school 

week comes from the SASS School Questionnaire.

SASS data can help answer the following questions: 

Has average teacher instructional time in each of the four subject areas alone (English, 

mathematics, social studies, and science) changed over time?

Has average teacher instructional time in the four subject areas combined (English, 

mathematics, social studies, and science) changed over time?

1 Teachers of self-contained classrooms instruct the same group of students all or most of the day in multiple subjects. 

These teachers were asked to report the amount of instruction they provided in four subjects, which is not necessarily the amount of instruction that their students received. Students may have received additional instruction in these 

subjects outside the classroom. 

•

•

U.S. Department of Education

NCES 2007–305

Contents

Introduction .......................... 1

Data and Purpose .................. 1

Findings ................................ 2

Summary ............................... 4

Methodology and Technical 

Notes ................................ 4

References ............................. 8

Appendix A. Standard Error 

Tables ............................... 9
2 NCES 2007-305

nated by English; this was true for all administrations of SASS 

(table 1). On average, about one-third of the student school 

week was used for English instruction, followed, in descending order, by mathematics, social studies, and science. Only 

in 1993–94 was this pattern interrupted, with no measurable 

difference between social studies and science instructional 

hours (each with an average of 3 hours per week). In 2003–

04, teachers of grades 1 through 4 provided an average of 

11.6 hours of English, 5.4 hours of mathematics, 2.5 hours of 

social studies, and 2.3 hours of science instruction per week. 

Trends in instructional time in each of the four subjects

English. On average, teachers of grades 1 through 4 spent 11 

hours per week on English instruction from 1987–88 through 

2003–04, with a low of 10.5 hours in 1990–91 and a high 

of 11.6 hours in 2003–04. The overall increase in English instruction between 1987–88 and 2003–04 (0.6 of an hour or 

36 minutes) amounts to about 22 more hours of English instruction over the course of an average 36-week school year. 

At the 2003–04 rate of 11.6 hours, this would yield about 

two additional weeks of English instruction.

However, as a percentage of total hours in the student school 

week, English instruction was not signifi cantly different in 

2003–04 than it was in 1987–88 (35.5 percent vs. 35.0 percent) 

(fi gure 1). The percentage of the student school week used for 

English instruction was higher in 2003–04 than in the intervening years (35.5 percent in 2003–04 versus 32.9 percent in 1990–

91, 34.0 percent in 1993–94, and 33.6 percent in 1999–2000). 

Mathematics. The average number of hours of mathematics 

instruction provided by self-contained teachers of grades 

Are teachers spending proportionally more time 

teaching any, or all, of the four subjects in relation to 

the total instructional time per week on all subjects 

and/or to the length of the student school week?

Although SASS collected data on specifi c subject instruction from all self-contained, team, and “pull-out” teachers 

in public and private schools, the analyses in this report include only regular, full-time public school teachers (including 

public charter school teachers) in self-contained classrooms. 

Among this subset, all self-contained classroom teachers of 

grades 1 through 4 are included.2 Teachers of self-contained 

classrooms were selected because they represent the majority 

of classroom instruction in the four subject areas at the primary-school level. For detailed information on the selection 

of the analysis sample, see the Methodology and Technical 

Notes of this report. 

The fi ndings reported below are descriptive and do not infer 

a cause for reported trends. All comparisons between groups 

were tested for statistical signifi cance using Student’s t statistics 

to ensure that the differences were larger than might be expected due to sampling variation. Unless stated otherwise, all differences in this report are signifi cant at the p < .05 level. Note 

that the intervals between SASS administrations vary. This 

should be considered when comparing trends across years.

Findings

Instructional hours overview

Overall, the instructional hours of public school teachers in 

self-contained classrooms of grades 1 through 4 were domi2

 Teachers in grades 5 through 8 are more likely to instruct fi xed-time-period 

classes focusing on one subject; thus, instructional time is most likely a function 

of class organization and subject-matter specialty, not teachers’ decisions. 

•

Table 1. Average number of hours and percentage of the student school week that public school teachers of fi rst- through fourth-grade, 

self-contained classrooms spent on each of four subjects, total instruction hours per week on four subjects, total time spent 

delivering all instruction per week, and average length of student school week, by selected characteristics: Selected years 

1987–88 through 2003–04

Characteristic

1987–88 1990–91 1993–94 1999–2000 2003–04

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

English 11.0 35.0 10.5 32.9 10.9 34.0 10.9 33.6 11.6 35.5

Mathematics 4.9 15.4 4.9 15.3 5.3 16.4 5.7 17.4 5.4 16.5

Social studies 2.8 8.7 2.9 9.1 3.0 9.5 2.9 8.9 2.5 7.6

Science 2.6 8.1 2.7 8.4 3.0 9.2 2.6 8.1 2.3 7.1

Total of four 

subjects 21.2 67.1 21.0 65.8 22.1 69.2 22.1 68.0 21.8 66.7

Total time spent 

delivering 

instruction 27.9 88.4 — — — — — — 29.6 90.6

Length of student 

school week 31.6 † 31.9 † 32.1 † 32.6 † 32.6 †

— Not available; data were not collected.

† Not applicable; student school week variable is used as the denominator.

NOTE: Due to school-level nonresponse, estimates in the row reporting “Length of student school week” are not available for all teachers in the sample. The 

reported estimates are for those teachers from responding SASS schools. Estimates in the “Percentage of student school week” columns are similarly affected. 

Detail may not sum to totals because of rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), “Public Teacher Data File,” 1987–88, 

1990–91, 1993–94, 1999–2000, and 2003–04; “Public School Data File,” 1987–88, 1990–91, 1993–94, 1999–2000, and 2003–04; “Charter Teacher Data File,” 

1999–2000; and “Charter School Data File,” 1999–2000.
NCES 2007-305 3

1 through 4 increased from 4.9 hours per week in 1987-

88 to 5.4 hours per week in 2003–04; however, it declined 

between 1999–2000 and 2003–04 (from 5.7 to 5.4 hours per 

week). Between the 1987–88 and 2003-04 school years, the 

additional 30 minutes of mathematics instruction per week 

would yield approximately 18 hours of additional instruction 

in a typical 36-week school year, or over 3 extra weeks of 

instruction at the 2003–04 rate of 5.4 hours per week. 

As seen in comparisons of hours of mathematics instruction 

per week, a similar pattern holds for mathematics instruction as a percentage of the student school week: an overall 

increase from 1987-88 through 2003–04 (from 15.4 percent 

to 16.5 percent of the student school week), but a decline between 1999–2000 and 2003–04 (from 17.4 percent to 16.5 

percent of the student school week). 

Social studies. In contrast to English instruction, the average 

number of hours that teachers of grades 1 through 4 spent on 

social studies instruction peaked in 1993–94 and then decreased 

in the two most recent administrations of SASS. In 1987–88, 

self-contained teachers of students in grades 1 through 4 provided an average of 2.8 hours of social studies instruction per 

week; in 2003–04, the average was 2.5 hours per week. This 

decrease of 0.3 of an hour (or 18 minutes per week) would add 

up to about 11 fewer hours of instruction over the course of a 

typical 36-week school year. At the average 2003–04 instruction rate of 2.5 hours per week, this would mean more than 4 

fewer weeks of social studies instruction. 

The same pattern seen in the hours of instruction holds when 

examining social studies instruction as a percentage of the student school week, with a peak of 9.5 percent of the student week 

spent on social studies instruction in 1993–94, but an overall 

decline from 8.7 percent in 1987–88 to 7.6 percent in 2003–04. 

Science. As with social studies instruction, the average number of hours that teachers of grades 1 through 4 spent on science instruction fi rst increased from 1987–88 through 1993–

94 and then decreased between the two most recent SASS 

administrations. In 1987–88, science was taught an average of 

2.6 hours per week; in 2003–04, the average was 2.3 hours per 

week. This decrease represents nearly 5 fewer weeks of instruction in science when following a 36-week school calendar and 

averaging about 2.3 hours of science instruction a week. 

Science instruction as a percentage of the student school 

week followed the same pattern as hours of science instruction, increasing between 1987–88 and 1993–94, but declining from 1993–94 to 2003–04. Overall, there was a decline 

of 1 percentage point from 1987–88 (8.1 percent) through 

2003–04 (7.1 percent). 

Trends in instructional time in four subjects combined

Despite overall declines in instructional time in social studies 

and science, total instructional time in the four subjects combined (English, mathematics, social studies, and science) increased from an average of 21.2 hours per week in 1987–88 

to 21.8 hours per week in 2003–04. This overall increase 

is due to increases in English and mathematics instruction 

that compensate for the decreases in social studies and science instruction. The 0.6 of an hour (36 minutes) per week 

increase would result in an extra 21.6 hours of combined 

instruction in the four subjects over a 36-week school year. 

At the 2003–04 rate of 21.8 hours per week, this translates 

to about an extra week of combined instruction in English, 

mathematics, science, and social studies.

Trends in instructional time as compared to total 

instruction and length of student school week

It is possible that both the total weekly instructional time 

and the length of the student school week increased so that 

the increase in instructional time in the four subjects did not 

come at the expense of instructional time in other subjects. 

In other words, if instruction in the four subjects increased at 

the same time as the student school week lengthened, it could 

be that no time was lost on the instruction of other subjects.

0

10

20

30

40

50

60

70

80

90

100

Percent

Subject

35.0 .0 32.9 34 33.6 35.5

15.4 15.3 16.4 17.4 16.5

8.7 9.1 9.5 8.9 7.6 8.1 8.4 9.2 8.1 7.1

1987−88

1990−91

1993−94

1999−2000

2003−04

English Mathematics Social studies Science

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), “Public Teacher Data File,” 1987–88, 1990–91, 

1993–94, 1999–2000, and 2003–04; “Public School Data File,” 1987–88, 1990–91, 1993–94, 1999–2000, and 2003–04; “Charter Teacher Data File,” 1999–2000; and 

“Charter School Data File,” 1999–2000.

Figure 1. Percentage of the student school week that public school teachers of fi rst- through fourth-grade, self-contained classrooms 

spent delivering instruction in four subjects: Selected years 1987–88 through 2003–04
4 NCES 2007-305

Total weekly instruction. Teachers were asked to report the 

total number of hours per week they spent delivering instruction in all subjects—not just for English, mathematics, social studies, and science—only in the 1987–88 and 2003–04 

administrations of SASS. Analyses showed that the average 

total instructional time, both in hours and as a percentage 

of the student school week, increased—from 27.9 hours in 

1987–88 (88.4 percent of the student school week) to 29.6 

hours in 2003–04 (90.6 percent of the student school week), 

a difference of 1.7 hours (or 102 minutes) per week. By this 

measure, time spent on all instruction increased over this 16-

year period, although there are no data to measure trends in 

the intervening school years.

Student school week. As shown in table 1, the average length 

of the student school week did, in fact, increase—from 31.6 to 

32.6 hours—from 1987–88 through 2003–04. Total instruction time in the four subjects also increased over the same 

period—from 21.2 to 21.8 hours. Although the increase in 

the school week was larger than the increase in combined 

instructional time in the four subjects, the percentage of the 

student school week spent on these four subjects did not decrease signifi cantly. It is important to remember that, despite 

apparent increases in the length of the student school week, 

SASS does not contain data that can identify what was added to the school week (e.g., a longer recess or lunch period 

vs. more instructional time), nor can it be used to determine 

whether this added time had an impact on learning.

Thus, while absolute hours of instruction in the four subjects 

increased between 1987–88 and 2003–04, the percentage of 

the student school week used for instruction in the four subjects did not change signifi cantly. 

Summary

Average instructional time in the four subjects—English, 

mathematics, social studies, and science—taught by public school teachers in self-contained classrooms of grades 1 

through 4 has changed between 1987–88 and 2003–04. Total instructional hours in the four subjects increased by an 

average of 36 minutes per week between the 1987–88 and 

2003–04 school years, whereas instructional time in all subjects increased by an average of 102 minutes per week. 

Over the fi ve SASS administrations, changes in instructional 

time in the individual subjects differ. English and mathematics 

instruction increased over this time period, while social studies and science instruction decreased. Although there was an 

overall decrease between the fi rst and last SASS administrations, average instruction in social studies and science grew 

in the intervening years, peaking in 1993–94. Despite these 

fl uctuations, total instructional time in the four subjects as 

a percentage of the student school week did not change signifi cantly between 1987–88 and 2003–04; it was about 67 

percent of the school week in each year. 

Between the most recent years for which data are available—1999–2000 and 2003–04—average instructional time 

for English increased; average instructional time for math, 

social studies, and science decreased. Finally, total instructional time in these four subjects did not change signifi cantly 

between these two years. 

Data from the next administration of SASS—in the 2007–08 

school year—will provide the next measure of changes in 

teacher instructional time in these four subject areas. 

Methodology and Technical Notes

This section provides a brief explanation of the methodology for all administrations of the Schools and Staffi ng Survey 

(SASS), with a particular focus on the public school teacher 

and public school elements. For complete information on 

sampling, data collection, response rates, and potential sources of bias in SASS administrations, please see the following 

reports, which can be found at http://nces.ed.gov/pubsearch/

getpubcats.asp?sid=003: 

1987–88 SASS: 1987–88 Schools and Staffi ng Survey: Sample Design and Estimation (NCES 91–127); 

and User’s Manual: 1987–88 Schools and Staffi ng 

Survey—Public School Data (NCES 91–136);

1990–91 SASS: 1991 Schools and Staffi ng Survey: 

Sample Design and Estimation (NCES 93–449); and 

An Exploratory Analysis of Response Rates in the 

1990–91 Schools and Staffi ng Survey (SASS) (NCES 

96–338);

1993–94 SASS: 1993–94 Schools and Staffi ng Survey: Data File User’s Manual: Volume I: Survey Documentation (NCES 96–142); and 1993–94 Schools 

and Staffi ng Survey: Sample Design and Estimation 

(NCES 96–089);

1999–2000 SASS: SASS—Schools and Staffi ng Survey (NCES 1999–352); and 

2003–04 SASS: Characteristics of Schools, Districts, 

Teachers, Principals, and School Libraries in the United States: 2003–04 Schools and Staffi ng Survey (NCES 

2006–313); and Documentation for the 2003–04 

Schools and Staffi ng Survey (NCES 2006–323).

Questionnaires from all administrations of SASS are available 

online at http://nces.ed.gov/surveys/SASS/questionnaire.asp.

Overview and history of SASS

SASS is conducted by the U.S. Census Bureau and sponsored 

by the National Center for Education Statistics (NCES). 

SASS has been conducted fi ve times: in school years 1987–88, 

1990–91, 1993–94, 1999–2000, and 2003–04. For each administration of SASS, NCES has reviewed the content of the 

questionnaires to expand, retain, or eliminate topics covered 

in the previous administration. Through these reviews, the 

survey’s capability for trend analysis is maintained, yet new 

topics are added to address current concerns. SASS provides 

valuable data for educators, researchers, and policymakers 

on public school districts; public (including public charter), 

private, and Bureau of Indian Affairs (BIA)-funded schools, 

principals, and teachers; and public and BIA school library 

media centers. SASS provides data on the characteristics and 

qualifi cations of teachers and principals, teacher hiring practices, professional development, class sizes, teacher instruction, and other conditions in schools across the nation.

This report uses data collected by the Public School Teacher 

Questionnaire and Public School Questionnaire from all fi ve 

•

•

•

•

•
NCES 2007-305 5

SASS administrations. Charter schools are a relatively new 

phenomenon. Sampling and questionnaire design were not 

tailored to capture information specifi c to charter schools 

prior to the 1999–2000 SASS administration. For the 1999–

2000 collection, separate samples and instruments were designed for charter schools and charter school teachers and 

there are separate data fi les for these populations for that 

year. In 2003–04, charter school samples and charter specifi c 

questions were embedded in the larger public school samples 

and questionnaires. However, charter schools and charter 

school teachers can be identifi ed and analyzed separately. 

Charter school teacher and charter school data are included 

in the 1999–2000 and 2003–04 analyses.

Public school and public school teacher estimates 

and target populations

SASS is designed to produce national, regional, and state estimates for public elementary and secondary schools and related components (i.e., teachers, principals, school districts, and 

school library media centers). Data from the SASS teacher questionnaires are designed to support comparisons between new 

and experienced teachers (3 years or less of experience vs. more 

than 3 years of experience) at the state level and between teachers by race and full- or part-time status at the national level.

Public school and public school teacher sample design

Public schools. The foundation of the public school sampling 

frame is the Common Core of Data (CCD) public elementary/

secondary school universe data fi le. The CCD fi le is based on 

data collected annually by NCES from each state education 

agency, and it is believed to be the most comprehensive list of 

public schools at the time of sample selection. Because of its 

scale, planning for SASS begins two years prior to data collection. Therefore, SASS uses the most recent CCD fi le available at the time for the sampling frame; the CCD released 

two years prior to the SASS school year (e.g., the 2003–04 

SASS used the 2001–02 CCD fi le). The SASS public school 

sample is a stratifi ed probability-proportionate-to-size (PPS) 

sample. All BIA-funded schools were automatically included 

in the SASS sample. In 2003–04, this produced a non-BIAfunded sample of 10,202 public schools and a BIA-funded 

sample of 166 schools.

Teachers. The sampling frame for SASS teachers consists 

of lists of teachers provided by schools in the SASS sample. 

Teachers are defi ned as staff who teach a regularly scheduled 

class to students in grades K–12. Respondents are instructed 

to exclude teachers of prekindergarten only, teachers of adult 

education or postsecondary education only, short-term substitutes, student teachers, teacher aides, day care aides, and 

librarians who only teach library skills. The sample of teachers is selected from all of the schools that provide teacher 

lists. On average, three to eight teachers were selected from 

each school. The maximum number of teachers selected per 

school was set at 20. The teacher sample size is limited in this 

way to avoid overburdening the schools, while allowing for 

a large enough teacher sample to meet the reliability requirements. For more information on the SASS sample selection, 

see the documents listed in the beginning of the Methodology 

and Technical Notes section.

Table 2 provides the unweighted sample sizes for all in-scope 

public school teachers and public schools selected for the full 

SASS sample in all administrations. 

Data collection

The data collection procedures for all questionnaires administered at the schools changed substantially for the 2003–04 

SASS. In previous administrations of SASS, self-administered 

questionnaires were mailed to the selected schools. Nonrespondents were contacted by telephone, using a computerassisted telephone interviewing (CATI) instrument. Finally, 

remaining nonrespondents were assigned to fi eld representatives who contacted them by telephone and/or by personal 

visits. Under that methodology, most respondents completed 

self-administered questionnaires, while some were interviewed by telephone.

During the 2003–04 SASS, fi eld representatives were responsible for all of the SASS data collection for each of the sampled schools, and nearly all questionnaires were completed 

directly by respondents as opposed to telephone interviews.

Response rates and nonresponse bias analysis

Unit response rates. Unit response rates are the rate at which 

the sampled units respond by substantially completing the 

questionnaire. The base-weighted unit response rates are the 

base-weighted number of interviewed cases divided by the 

base-weighted number of eligible cases. The base weight for 

each sampled unit is the inverse of the probability of selection. Table 3 provides the base-weighted unit response rates 

and overall response rates for public school teachers and 

public schools in all SASS administrations.

Item response rates. The weighted item response rates are the 

fi nal weighted number of sample cases responding to an item 

Table 2. Unweighted sample sizes for the full SASS public school teacher and public school sample: Selected years 1987–88 through 2003–04

Respondent 1987–88 1990–91 1993–94 1999–2000 2003–04

Public school teachers 56,242 56,051 56,736 61,298 53,188

Public schools 9,317 9,688 9,960 11,136 10,368

NOTE: Sample sizes include all in-scope public school teachers and public schools (including traditional public and public charter sectors where applicable). In 

1990–91, 1993–94, 1999–2000, and 2003–04 separate sample sizes were available for public and BIA sectors. However, they are reported together in this table. 

Separate public and BIA totals were not reported in 1987–88. Totals from 1987–88 can not be confi rmed, but were taken from the report Qualifi cations of the 

Public School Teacher Workforce: Prevalence of Out-of-Field Teaching, 1987–88 to 1999–2000 Revised (NCES 2002–603).

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), Qualifi cations of the Public School Teacher 

Workforce: Prevalence of Out-of-Field Teaching, 1987–88 to 1999–2000 Revised (NCES 2002–603), 1990–91 Schools and Staffi ng Survey: Data File User’s Manual 

Volume I: Survey Documentation (NCES 93–144), 1993–94 Schools and Staffi ng Survey: Data File User’s Manual Volume I: Survey Documentation (NCES 96–142), 

1999–2000 Schools and Staffi ng Survey (SASS) Data File User’s Manual (NCES 2004–303), and Characteristics of Schools, Districts, Teachers, Principals, and School 

Libraries in the United States: 2003–04 Schools and Staffi ng Survey (NCES 2006–313).
6 NCES 2007-305

each imputed item so that it is possible for data users to 

identify which items were imputed, how the imputations 

were performed, and whether or not to include the imputed 

data in their analysis. 

Weighting, variance estimation, and tests of 

signifi cance

Each SASS data fi le contains a fi nal weight and a set of replicate weights. The fi nal weights are needed so that the sample 

estimates refl ect the target survey population when analyzing the data. For these analyses, the fi nal teacher weight was 

used so that sample estimates refl ect the target teacher population. In 1999–2000 and 2003–04, the fi nal weight variable 

is TFNLWGT. In 1987–88, 1990–91, and 1993–94, the fi nal 

weight variable is TCHWGT. 

In surveys with complex sample designs, such as SASS, direct estimates of sampling errors that assume a simple random sample will typically underestimate the variability in the 

estimates. The SASS sample design and estimation include 

procedures that deviate from the assumption of simple random sampling. For this reason, the preferred method of calculating sampling errors is replication. Each SASS data fi le 

includes a set of replicate weights designed to produce variance estimates. 

The tests of signifi cance used in this analysis are based on 

Student’s t statistics. The formula used to compute Student’s 

t statistics is as follows:

E1

 and E2 are the fi rst and second estimates being compared, 

and se1 and se2 are the corresponding standard errors. 

Analysis sample

The following is a summary of the restrictions made to the 

full SASS sample in defi ning the subsample used in this report. 

The analysis sample for this report includes teachers who

teach students in one (or more) of grades 1 through 4;

report self-contained classroom organization;

•

•

divided by the fi nal weighted number of sample cases eligible 

to answer the item. Rates are reported for all survey items on 

the SASS Public School and Public Teacher data fi les. Also 

included, where applicable, are response rates of Charter 

School and Charter Teacher data fi les. 

In 2003–04, the item response rates ranged from 71 to 100 

percent on the Public School data fi le and 44 to 100 percent 

on the Public Teacher data fi le. In 1999–2000, the item response rates ranged from 67 to 100 percent on the Public 

School data fi le and 39 to 100 percent on the Charter School 

data fi le. Also in 1999–2000, item response rates ranged 

from 48 to 100 percent on the Public Teacher data fi le and 

16 to 100 percent on the Charter Teacher data fi le. In 1993-

94, item response rates on the Public School data fi le ranged 

from 83 to 100 percent and 71 to 100 percent on the Public 

Teacher data fi le. Ranges in item response rates for 1990–91 

and 1987–88 are not available in the SASS documentation; 

however, items with response rates lower than 75 percent are 

recorded. No variable used in either administration has a response rate below 75 percent. In fact, no item used in this 

analysis has a response rate lower than 75 percent. 

Nonresponse bias analysis. A comprehensive nonresponse 

bias analysis was conducted for each SASS data fi le for all 

survey administrations. Evidence of substantial bias due to 

unit- or item-level nonresponse was not found in any of the 

data fi les. For information on computing different types of 

response rates see NCES Standard 1–3 (U.S. Department of 

Education 2003).

Imputation procedures 

SASS is a fully imputed dataset. In general, missing values are 

fi lled during one of three stages of imputation: (1) survey data 

are imputed with a valid response using data from other items 

in the same questionnaire or from other related sources, (2) 

data are imputed from items found on the questionnaires of 

respondents who have certain characteristics in common or 

from the aggregated answers of similar questionnaires, and 

(3) the remaining unanswered items are imputed clerically 

by Census Bureau analysts. A numerical fl ag is assigned to 

2

2

2

1

1 2

se se

E E

+

− t =

Table 3. Base-weighted unit response rates and weighted overall response rates, by respondent: Selected years 1987–88 through 2003–04

Respondent 1987–88 1990–91 1993–94 1999–20001 2003–04

Public school teachers

Base-weighted unit response rate 86.4 90.3 88.2 83.1 84.8

Weighted overall response rate n/a 2 85.9 83.8 76.6 75.7

Public schools

Base-weighted unit response rate 91.9 95.3 92.3 88.5 80.8

Weighted overall response rate † † † † †

† Not applicable.

1 1999–2000 response rates were calculated separately for public charter school teachers and public charter schools. The base-weighted unit response rate for 

public charter school teachers was 78.6 percent. The overall response rate for public charter school teachers was 71.8 percent. For public charter schools, the 

base-weighted unit response rate was 86.1 percent.

2 The Teacher Listing Form response rates for 1987–88 are not recorded in any of the data fi le documentation and are unknown.

NOTE: Base-weighted unit response rates were weighted using the inverse of the probability of selection (base weight). The overall response rate is the baseweighted teacher questionnaire response rate multiplied by the base-weighted response rate of the Teacher Listing Form.

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey, special tabulations from the “Public School” and 

“Public Teacher” Documentation Data Files, 2003–04; Qualifi cations of the Public School Teacher Workforce: Prevalence of Out-of-Field Teaching, 1987–88 to 

1999–2000 Revised (NCES 2002–603), 1990–91 Schools and Staffi ng Survey: Data File User’s Manual Volume I: Survey Documentation (NCES 93–144), 1993–94 

Schools and Staffi ng Survey: Data File User’s Manual Volume I: Survey Documentation (NCES 96–142), 1999–2000 Schools and Staffi ng Survey (SASS) Data File 

User’s Manual (NCES 2004–303), and Characteristics of Schools, Districts, Teachers, Principals, and School Libraries in the United States: 2003–04 Schools and 

Staffi ng Survey (NCES 2006–313).
NCES 2007-305 7

count for the total amount of instruction occurring in their 

classrooms (only one team teacher in any class is included 

in the survey). “Pull-out” teachers were not examined because of their focus on specialized instruction in one subject 

(e.g., English/language arts or special education)—“pull-out” 

teachers would show little variability in instructional hours 

across subjects. 

Preliminary analyses were conducted to confi rm that the subsample of self-contained fi rst- through fourth-grade teachers 

included a stable population of teachers in “average” classrooms. The distribution of classroom organization types 

was examined for all regular, full-time teachers of grades 

1 through 4 over all fi ve SASS administrations. The results 

show that self-contained teachers consistently make up about 

two-thirds of this teacher subsample (table 4). 

In addition, the distribution of main assignments for teachers in each classroom organization type and each SASS year 

was run (results for all years available upon request). Several 

consistent patterns emerged:

The majority of departmentalized teachers fall into 

four main assignments: elementary education, English/language arts, mathematics/computer science, 

and arts/music. Data on instructional hours were not 

collected for departmentalized teachers.

The majority of elementary enrichment teachers fall 

into either arts/music or health/physical education, 

with a small portion listing elementary education. 

Data on instructional hours were not collected for 

elementary enrichment teachers.

The large majority of self-contained teachers report 

an elementary education main assignment. A small 

portion also reports special education. 

The majority of team teachers report a main assignment of elementary education. A portion also reports 

special education. 

Finally, among “pull-out” teachers, the majority report either special education or English/language arts. 

Results of these preliminary analyses confi rm that the fi ndings and conclusions in the report apply to both a stable majority of fi rst- through fourth-grade classroom teachers and 

the instruction they offer in the four subjects. 

•

•

•

•

•

report a regular, full-time teaching status; and

teach in a public school (including traditional public 

and public charter schools).

Grade range. The fi rst- through fourth-grade range was 

chosen because the majority of teachers at this level teach in 

self-contained classrooms where instructional time is likely 

to vary. First- through fourth-grade teachers also represent 

the traditional “primary-level” teachers, as defi ned by SASS. 

Teachers of students in grades 5 through 8 are considered upper-elementary and middle school teachers. In these grades, 

teachers are more likely to instruct departmentalized classes 

of fi xed time periods where instruction is most likely a function of class scheduling and classroom organization, not 

teachers’ decisions. 

Though in a single classroom, self-contained teachers could 

instruct students in multiple grade levels within the fi rstthrough fourth-grade range or students in a grade (or grades) 

within the range and students in a grade higher and/or lower. 

Unpublished analyses comparing estimates showed few significant differences between all regular, full-time, self-contained 

teachers of grades 1 through 4 as compared to those teaching only within the fi rst- through fourth-grade range (i.e., no 

grade higher or lower). Therefore, teachers with classrooms 

combining students in grades 1 through 4 and students outside grades 1 through 4 are included in these analyses.

Classroom organization. Instruction in the four subject areas 

occurs by teachers of all classroom organization types; however, this report sought to include the “typical” classroom 

teacher of the four subject areas. Self-contained teachers were 

selected because they instruct the same group of students for 

all or most of the day in multiple subjects and were believed 

to represent the majority of teachers of grades 1 through 4. 

Other classroom organization types include departmentalized 

(instructing several classes of different students in specifi c subjects), elementary enrichment class (elementary teacher who 

teaches only one subject), team teaching (two or more teachers 

in the same class jointly responsible for instruction of a single 

group of students), and “pull-out” class (instructing selected 

students taken from regular classes in areas of specifi c needs). 

SASS data on instructional hours were collected only from 

self-contained, team, and “pull-out” teachers. Team teachers 

were not analyzed in this report because SASS cannot ac-

•

•

Table 4. Number and percentage of public school teachers who teach any of grades 1 through 4, by classroom organization: Selected 

years 1987–88 through 2003–04

Classroom

organization

1987–88 1990–91 1993–94 1999–2000 2003–04

Number Percent Number Percent Number Percent Number Percent Number Percent

Departmentalized 102,068 12.7 73,725 8.3 54,760 6.3 57,190 5.7 75,568 6.9

Elementary 

enrichment class — — 54,246 6.1 82,826 9.5 75,024 7.5 108,489 9.9

Self-contained class 543,710 67.8 604,298 68.0 581,821 66.6 683,539 68.1 723,046 66.2

Team teaching 44,275 5.5 58,912 6.6 66,996 7.7 76,219 7.6 37,475 3.4

“Pull-out” class 112,278 14.0 97,484 11.0 87,602 10.0 111,500 11.1 147,428 13.5

— Not available; data were not collected.

NOTE: Includes regular, full-time teachers who teach students in any of grades 1, 2, 3, or 4, regardless of whether they teach students in additional grades.

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), “Public Teacher Data File,” 1987–88, 

1990–91, 1993–94, 1999–2000, and 2003–04; and “Charter Teacher Data File,” 1999–2000.
8 NCES 2007-305

Unpublished analyses also examined the stability of the fi rstthrough fourth-grade student population. In SASS, class enrollments are reported by the teacher. Therefore, students can 

be counted multiple times by teachers of different classroom 

types (e.g., an art teacher counts the same fi rst-grade students 

that a self-contained fi rst-grade teacher counts). This makes it 

diffi cult to accurately measure student population changes by 

classroom type. However, average class sizes for teachers in the 

report subsample were relatively stable across the fi ve administrations; ranging from 20.2 to 23.0 students. These fi ndings, 

combined with the stability of the teacher population in question, should lessen concerns that changes in teacher or student 

populations are a cause of changes in instructional time.

Teaching status. Part-time teachers, substitute teachers, teacher aides, or other professional staff (e.g., administrators or 

counselors) were not included in the analysis sample. These 

teachers and staff either were not asked to report the hours 

per week they spent teaching different subjects or, if asked, are 

not comparable to full-time teachers because of the occasional 

nature or unspecifi ed time frame of their instruction. 

Sector of school. The analyses include only public school 

teachers (traditional public and public charter school teachers). Teachers in private schools and BIA-funded schools are 

not included.

Table 5 shows the public school teacher and public school 

sample sizes in each administration examined in this report.

Table 5. Unweighted sample size of regular full-time, fi rst- through fourth-grade public school teachers in self-contained classrooms and their 

corresponding public schools: Selected years 1987–88 through 2003–04

Respondent 1987–88 1990–91 1993–94 1999–2000 2003–04

Public school teachers 7,948 7,643 6,739 6,495 5,877

Public schools 7,511 7,403 6,248 5,959 5,508

NOTE: Due to school-level nonresponse, school data are not available for all teachers. Tables in the body of the report are noted where applicable.

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), “Public Teacher Data File,” 1987–88, 1990–

91, 1993–94, 1999–2000, and 2003–04; “Public School Data File,” 1987–88, 1990–91, 1993–94, 1999–2000, and 2003–04; “Charter Teacher Data File,” 1999–2000; 

and “Charter School Data File,” 1999–2000.

This report was written by staff at the Education Statistics Services Institute (ESSI), which is funded by NCES and composed of staff from the 

American Institutes for Research (AIR) and a number of partner organizations. The authors would like to acknowledge several people for the 

valuable feedback they provided during the writing of this Statistics in Brief. Their comments improved the quality of this brief and for that we 

would like to thank Greg Strizek, Pia Peltola, Deanna Lyter, Sandy Eyster, and Martin Hahn of AIR; Greg Orlofsky and Michael Hurwitz, formerly 

of AIR. We would also like to thank Elizabeth Willis of Quality Information Partners, Inc. and, from NCES, Kathryn Chandler, Kerry Gruber, Jeff 

Owings, Stephen Provasnik, Chris Chapman, and the NCES/ESSI Technical Review team.

For more information on this Statistics in Brief or SASS, please contact: Kathryn Chandler, Program Director, Elementary/Secondary Sample 

Survey Studies Program, Elementary/Secondary and Libraries Studies Division (ESLSD), National Center for Education Statistics, 1990 K Street NW, 

Washington, DC 20006, or call (202) 502-7486 or e-mail Kathryn.Chandler@ed.gov.

References

Berliner, David C. (1990). What’s All the Fuss About Instructional 

Time? In M. Ben-Peretz and R. Bromme (Eds.), The Nature 

of Time in Schools: Theoretical Concepts, Practitioner 

Perceptions. New York: Teachers College Press.

Coates, Dennis. (2003). Education Production Functions Using 

Instructional Time as an Input. Education Economics, 11(3): 

273–292.

Carroll, John B. (1963). A Model of School Learning. Teachers 

College Record, 64(8): 723–733.

Dreeben, Robert, and Gamoran, Adam. (1986). Race, Instruction, and 

Learning. American Sociological Review, 51(5): 660–669. 

National Commission on Excellence in Education. (1983). A Nation 

At Risk: The Imperative for Educational Reform. Available 

online: http://www.ed.gov/pubs/NatAtRisk/index.html. 

Accessed: February 15, 2007. 

U.S. Department of Education. (2003). NCES Statistical Standards 

(NCES 2003–601). Washington, DC: National Center for 

Education Statistics.
NCES 2007-305 9

Table A–1. Standard errors for Table 1: Average number of hours and percentage of the student school week that public school teachers 

of fi rst- through fourth-grade, self-contained classrooms spent on each of four subjects, total instruction hours per week on 

four subjects, total time spent delivering all instruction per week, and average length of student school week, by selected 

characteristics: Selected years 1987–88 through 2003–04

Characteristic

1987–88 1990–91 1993–94 1999–2000 2003–04

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

Average 

number 

of hours

Percent 

of student 

school week

English 0.07 0.23 0.08 0.25 0.07 0.26 0.08 0.26 0.11 0.33

Mathematics 0.03 0.09 0.04 0.14 0.04 0.14 0.04 0.15 0.04 0.13

Social studies 0.04 0.12 0.05 0.16 0.04 0.13 0.03 0.11 0.03 0.10

Science 0.04 0.13 0.04 0.14 0.05 0.15 0.03 0.10 0.03 0.10

Total of four 

subjects 0.10 0.33 0.13 0.43 0.12 0.46 0.12 0.41 0.14 0.46

Total time spent 

delivering 

instruction 0.10 0.41 † † † † † † 0.10 0.35

Length of student 

school week 0.05 † 0.06 † 0.06 † 0.06 † 0.07 †

† Not applicable.

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), “Public Teacher Data File,” 1987–88, 

1990–91, 1993–94, 1999–2000, and 2003–04; “Public School Data File,” 1987–88, 1990–91, 1993–94, 1999–2000, and 2003–04; “Charter Teacher Data File,” 1999–

2000; and “Charter School Data File,” 1999–2000.

Table A–2. Standard errors for Table 4: Number and percentage of public school teachers who teach any of grades 1 through 4, by

classroom organization: Selected years 1987–88 through 2003–04

Classroom

organization

1987–88 1990–91 1993–94 1999–2000 2003–04

Number Percent Number Percent Number Percent Number Percent Number Percent

Departmentalized 2,672.4 0.28 3,073.7 0.32 3,200.5 0.35 3,662.7 0.35 5,381.9 0.49

Elementary 

enrichment class † † 2,877.7 0.31 3,910.9 0.41 4,033.4 0.40 5,652.7 0.49

Self-contained class 4,964.1 0.43 8,871.2 0.67 11,391.2 0.70 10,826.5 0.66 18,939.3 0.98

Team teaching 2,340.7 0.29 3,704.6 0.41 3,165.3 0.36 4,606.7 0.45 3,821.7 0.35

“Pull-out” class 3,413.5 0.37 3,802.2 0.42 4,051.3 0.39 4,759.5 0.45 9,919.4 0.87

† Not applicable.

NOTE: Includes regular, full-time teachers who teach students in any of grades 1, 2, 3, or 4, regardless of whether they teach students in additional grades.

SOURCE: U.S. Department of Education, National Center for Education Statistics, Schools and Staffi ng Survey (SASS), “Public Teacher Data File,” 1987–88, 

1990–91, 1993–94, 1999–2000, and 2003–04; and “Charter Teacher Data File,” 1999–2000.

Appendix A. Standard Error Tables