Instruction Time, Classroom Quality, and Academic Achievement

Steven G. Rivkin and Jeffrey C. Schiman

February 2013

Policy Background

• Increase in the quantity of an input would be expected to increase output in virtually all circumstances– Evidence on school resources suggests the

presence of extensive inefficiencies in public schools

– Raises questions about the benefits of increased instructional time

Longer Instruction Time and Higher Achievement

• Poland substantially increased time devoted to 9th grade mathematics instruction in 2001 by over 80 minutes per week on average

• Instruction time at KIPP Charter schools is 60% higher than the US average

• In each case a number of other factors also differ, raising uncertainty about the effects of instructional time

Existing Literature

• Supports positive effect of instructional time• Most research designs fail to account for the

non-random allocation of instructional time• Higher achieving students attend schools with

a greater emphasis on academics• Lavy (2010) is an exception– Method uses within student and school time

variation by subject– Deficiencies of 2006 categorical time data

Conceptual Framework

• Allocation of instruction time depends upon many factors including ability

• Benefit of additional time likely depends on classroom quality– Teacher skills– Curriculum– Student behavior

• Behavior and instruction quality may vary with time

Empirical Framework

• Use panel data methods to account for differences in ability and quality of instruction that could be related to instructional time

• Aggregate instructional time information to the school-grade-subject level to mitigate problems introduced by student class assignments

• Use survey questions to generate measures of learning environment that will be used to investigate heterogeneity in time effects

Structure of 2009 PISA data

• Tests in mathematics and language arts• 15 year old students are in multiple grades• School representative reports class length– Typically samefor all grades and subjects

• Students report number of classes attended• School representative answers questions on

classroom environment

Empirical model

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School by grade Fixed Effects

• School by grade fixed effects accounts for student and school differences common across subjects (similar to student fixed effects)

• Subject specific factors that vary at the individual or school level could introduce bias

Accounting for subject specific factors

• Country by grade by subject fixed effects account for factors such as national curricula, investments, or emphasis

• School by subject fixed effects account for differences among subjects in ability, teacher skill, or quality of curriculum

Identification with school by subject fixed effects

• Cumulative nature of learning attenuates estimates– Assumption that 9th grade instructional time has

no effect on 10th grade achievement likely violated• Uses within subject instructional time

differences between grades– Assumes cohort differences in ability and grade

differences in the quality of instruction are not related to grade differences in instructional time

Presentation of Results

• Distribution of instructional time and corresponding test score differences

• OLS and Fixed Effect Estimates of weekly minutes and weekly classes effects

• Non-linear estimates of instructional time effects

• Construction of classroom quality variable• Estimates of interaction with quality

Mathematics

Language Arts 0-2 3 4 5 6+

0-2 15,776 7,690 3,943 2,580 1,687

3 6,565 32,226 19,054 6,942 2,385

4 5,433 20,260 68,412 23,464 5,623

5 1,930 4,410 27,530 62,870 11,384

6+ 1,081 1,586 9,746 16,800 36,011

Joint Distribution of Classes Per Week

Mathematics

Language Arts 0-2 3 4 5 6+

0-2 -2.3 3.5 -2.2 5 11.5

3 1.4 -1 4.6 3.2 6.6

4 -4.3 -1.4 0.4 0 9.2

5 -12.2 -3.7 -9.6 -1.3 5.6

6+ -14.7 3.1 -0.2 0.2 10.5

Mathematics minus reading score difference by numbers of classes

Table 3. Estimated Effects of Weekly Instructional Minutes and Classes per Week on AchievementPanel A:

Weekly Minutes of Instruction 0.072*** 0.030*** 0.018*** 0.006

(0.008) (0.005) (0.007) (0.009)Panel B:

Weekly Number of Classes 5.597*** 2.426*** 1.142*** 0.270

(0.495) (0.335) (0.482) (0.482)

School-by-grade fixed effects N Y N Y

School-by-subject fixed effects N N Y Y

Table 4. Estimated Effects of Weekly Minutes

Weekly Minutes 0.069*** 0.108***

(0.014) (0.018)

Weekly Minutes Squared -0.00006*** -0.00013***

(0.00002) (0.00002)

School-by-grade fixed effects Y N

School-by-subject fixed effects N Y

Table 6. Estimated Effects of Classes per Week on Achievement, By Class Length

40 3.251*** 0.905(0.821) (0.644)45 1.850*** 1.071*(0.531) (0.564)50 3.263*** 1.910***(0.60) (0.58)55 4.017*** 1.988***(0.94) (0.64)60 3.250*** 0.946(1.11) (0.74)

School-by-grade fixed effects Y N

Variation in benefits of instructional time by classroom quality

• Hindrances to learning– Disruption– Lower teacher quality– Ineffective curriculum

• Quality of learning environment might decrease as class length increases

Measurement of Learning Hindrances

Teachers’ low expectations of students

Student absenteeism

Poor student-teacher-relations

Disruption of classes by students

Teachers not meeting individual student needs

Teacher absenteeism

Students skipping classes

Students lacking respect for teachers

Table 8. Estimated Effects of Instructional Time, by Classroom Hindrances

Weekly Minutes of Instruction 0.080*** 0.051*

(0.017) (0.028)Weekly minutes-by-Classroom Hindrances -0.020*** -0.013

(0.006) (0.010)

Weekly Number of Classes 4.560*** 3.338**(1.033) (1.692)

Weekly Classes-by- Classroom Hindrances -0.824** -0.819

(0.369) (0.607)School-by-grade fixed effects Y NSchool-by-subject fixed effects N Y

Summary and Policy Implications

• Evidence supports the hypothesis that additional instructional time raises achievement– Significant school by subject estimates likely

provide a lower bound on effects• Modest diminishing returns to additional time• Evidence that benefits depend on quality of

learning environment

Determinants of return to instructional time

• Quality of learning environment• Opportunity costs in terms of other subjects

foregone or financial cost of additional time at school

• Return also depends on other benefits of longer time in school potentially including– reduced crime and deviant behavior– Improvements in other valued outcomes