# **1. Introduction**

Teacher salaries are typically the single largest investment that countries make in basic education, and evidence shows that teachers explain a significant share of variation across students’ achievement (Araujo et al. 2016, Bold et al. 2019; Dobbie and Fryer 2013). At the same time, this achievement is poorly correlated with teachers’ observable characteristics including age, gender, education, experience and even hours in the school (Aaronson et al. 2007; Kane and Staiger 2008; Rockoff et al. 2008). The implication is that factors such as teachers’ content knowledge, pedagogical knowledge, as well as classroom behaviors and practices are potentially important determinants of students' academic performance. This paper compares various approaches to measuring these factors and explores the extent to which they are associated with student test scores—both individually and collectively.

A growing literature has documented significant shortfalls in service delivery in education across countries (World Bank 2018). Surveys of teacher absenteeism in low- and middle-income countries routinely show absence rates of between 15 and 20 percent on any given day (Chaudhury et al 2006, World Bank 2003, Das et al 2007). The Service Delivery Indicators (SDI) program (www.sdindicators.org) has documented teacher absence rates of over 20 percent in Togo and Uganda, and over 40 percent in Mozambique. In addition, even when teachers are in school, they are frequently absent from the classroom: for example, the 2014 round of SDI in Tanzania revealed that while only 15 percent of teachers were absent from the school, 47 percent of teachers (including those absent from school) were not in class at the time of an unannounced visits (Martin and Wane 2016). Even when present, teachers are devoting significant amounts of time to non-teaching and learning activities, such as classroom management (Abadzi 2009; Bruns and Luque 2015). The cumulative result is that students are receiving only a fraction of the scheduled teaching time as actual learning time: across 7 Sub-Saharan African countries, whereas scheduled teaching time was on average 5 hours and 27 minutes per school day—actual teaching time was on average 2 hours and 46 minutes (Bold et al. 2017).

In order to shed light on the measurement of these issues and their implications, we administered four different classroom observation instruments—from the Service Delivery Indicators, the Stallings Observation System, the Classroom Assessment Scoring System, and the recently developed _Teach_ classroom observation instrument—in about 100 schools across four regions of Tanzania. The research design is such that various combinations of tools were administered to various combinations of teachers so these data can be used to explore the commonalities and differences in the behaviors and practices captured by each tool, the internal properties of the tools (for example how stable they are across enumerators, or how various indicators relate to one-another), and how variables collected by the various tools compare to each other. In addition to insights on the tools themselves, we leverage measures of teacher and student 2