The effects of lost classroom time

12 Apr 2022

What are the effects of lost instructional time in the classroom? This question has recently gained prominence due to Covid-19-related school closures affecting millions of students around the world. Although standard in-person classes have been substituted by remote instruction to some extent, evidence has suggested that pupils made little to no progress while learning from home.

New research, to be presented at the annual conference of the Royal Economic Society, investigates the consequences of lost classroom time for labour market success over a lifetime. To do this, it examines a previous example of significant lost time, when school reforms in Germany led to the shortening of two school years in 1966/67.

This unusual example allows long-term effects to be studied in detail, something that is otherwise difficult. The study by Kamila Cygan-Rehm, of the Leibniz Institute for Educational Trajectories (LIfBi) at the University of Bamberg, finds adverse effects on labour income which persist over nearly the entire occupational career.

She estimates that, despite some compensatory measures such as additional homework, one year of lost in-class instruction decreases lifetime earnings by 3%. This effect is partly driven by lower labour supply during prime working ages, which decreases by 2%. There are no meaningful effects on educational credentials. Instead, the author shows that long-lasting effects on cognitive abilities and personality traits are plausible channels behind the impaired labour market performance.

In more detail: the study estimates the lifetime effects of lost in-class instruction by evaluating the impact of two shortened school years in Germany in 1966/67, a consequence of changing the starting date of the school year. Each short school year substantially reduced the in-school instructional time, but there was much emphasis on leaving the core curriculum unchanged. Thus, the educational authorities introduced some compensatory measures such as additional homework assignments in core subjects (maths and German), reduced instructional time in other subjects, and cancellations of co-curricular activities. Generally, students and parents bore the responsibility for ensuring that learning continued as normal.

The last birth cohorts of students affected by the short school years are currently close to reaching the statutory retirement age. Thus, using social security records with detailed employment biographies, the author of the new study can examine their earnings and employment over nearly entire occupational careers. The statistical approach, called a difference-in-differences design, relies on differential exposure to the short school years across the federal states and birth dates. It uses data on nearly 300,000 people who started school between 1950 and 1970.

The analysis yields three key results.

First, there are adverse effects on earnings that persist over nearly the entire occupational career. These negative impacts sum up to a 3% reduction in lifetime earnings from one year of lost in-school instruction.

Second, during prime working ages, affected individuals also spent fewer days in employment, which decreased by 2% and partly explain the earnings losses.

Finally, there are no meaningful impacts on completed educational attainment, which could reflect teachers being more lenient and letting “marginal” students slide through. Nevertheless, using complementary survey data, the study shows long-lasting effects on cognitive abilities and personality traits, which are plausible channels behind lower labour income.

It seems that, unless remediated, learning losses can be significant. These findings are also relevant in the context of other situations that keep students out of the classroom, such as natural disasters, inclement weather, teacher strikes, or long summer holidays.

Overall, this study documents adverse consequences of lost in-school instruction for the development of important skills and labour market performance. The findings call for immediate interventions to remedy learning losses that occur when students are kept out of the classroom.


Kamila Cygan-Rehm (Leibniz Institute for Educational Trajectories - LIfBi at the University of Bamberg)


Twitter: @CyganRehm

Notes to Editors:

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