Healing Covid-19’s Educational Losses: What is the Evidence?

I’ve written several blogs (here, here, here, here, here, and here) on what schools can do when they finally open permanently, to remedy what will surely be serious harm to the educational progress of millions of students. Without doubt, the students who are suffering the most from lengthy school closures are disadvantaged students, who are most likely to lack access to remote technology or regular support when their schools have been closed.

 Recently, there have been several articles circulated in the education press (e.g., Sawchuk, 2020) and newsletters laying out the options schools might consider to greatly improve the achievement of students who lost the most, and are performing far behind grade level.

The basic problem is that if schools simply start off with usual teaching for each grade level, this may be fine for students at or just below grade level, but for those who are far below level, this is likely to add catastrophe to catastrophe. Students who cannot read the material they are being taught, or who lack the prerequisite skills for their grade level, will experience failure and frustration. So the challenge is to provide students who are far behind with intensive, additional services likely to quickly accelerate their progress, so that they can then profit from ordinary, at-grade-level lessons.

In the publications I’ve seen, there have been several solutions frequently put forward. I thought this might be a good time to review the most common prescriptions in terms of their evidence basis in rigorous experimental or quasi-experimental research.

Extra Time

One proposal is to extend the school day or school year to provide additional time for instruction. This sounds logical; if the problem is time out of school, let’s add time in school.

The effects of extra time depend, of course, on what schools provide during that additional time. Simply providing more clock hours in which typical instruction is provided makes little difference. For example, in a large Florida study (Figlio, Holden, & Ozek, 2018), high-poverty schools were given a whole hour every day for a year, for additional reading instruction. This had a small impact on reading achievement (ES=+0.09) at a cost of about $800 per student, or $300,000-$400,000 per school. Also, in a review of research on secondary reading programs by Baye, Lake, Inns & Slavin (2019), my colleagues and I examined whether remedial programs were more effective if they were provided during additional time (one class period a day more than what the control group received for one or more years) or if they were provided during regular class time (the same amount of time the control group also received). The difference was essentially zero. The extra time did not matter. What did matter was what the schools provided (here and here).

After-School Programs

Some sources suggest providing after-school programs for students experiencing difficulties. A review of research on this topic by Kidron & Lindsay (2014) examined effects of after-school programs on student achievement in reading and mathematics. The effects were essentially zero. One problem is that students often did not attend regularly, or were poorly motivated when they did attend.

Summer School

As noted in a recent blog, positive effects of summer school were found only when intensive phonics instruction was provided in grades K or 1, but even in these cases, positive effects did not last to the following spring. Summer school is also very expensive.


By far the most effective approach for students struggling in reading or mathematics is tutoring (see blogs here, here, and here). Outcomes for one-to-one or one-to-small group tutoring average +0.20 to +0.30 in both reading and mathematics, and there are several particular programs that routinely report outcomes of +0.40 or more. Using teaching assistants with college degrees as tutors can make tutoring very cost-effective, especially in small-group programs.

Whole-School Reforms

There are a few whole-school reforms that can have substantial impacts on reading and mathematics achievement. A recent review of our elementary school reform model, Success for All (Cheung et al., 2020), found an average effect size of +0.24 for all students across 17 studies, and an average of +0.54 for low achievers.

A secondary reform model called BARR has reported positive reading and mathematics outcomes for ninth graders (T. Borman et al., 2017)


Clearly, something needs to be done about students returning to in-person education who are behind grade level in reading and/or mathematics. But resources devoted to helping these students need to be focused on approaches proven to work. This is not the time to invest in plausible but unproven programs. Students need the best we have that has been repeatedly shown to work.


Baye, A., Lake, C., Inns, A., & Slavin, R. (2019). Effective reading programs for secondary students. Reading Research Quarterly, 54 (2), 133-166.

Borman, T., Bos, H., O’Brien, B. C., Park, S. J., & Liu, F. (2017). i3 BARR validation study impact findings: Cohorts 1 and 2. Washington, DC: American Institutes for Research.

Cheung, A., Xie, C., Zhang, T., Neitzel, A., & Slavin, R. E. (2020). Success for All: A quantitative synthesis of evaluations. Manuscript submitted for publication. (Contact us for a copy.)

Figlio, D. N., Holden, K. L., & Ozek, U. (2018). Do students benefit from longer school days? Regression discontinuity evidence from Florida’s additional hour of literacy instruction. Economics of Education Review, 67, 171-183. https://doi.org/10.1016/j.econedurev.2018.06.003

Kidron, Y., & Lindsay, J. (2014). The effects of increased learning time on student academic and nonacademic outcomes: Findings from a meta‑analytic review (REL 2014-015). Washington, DC: U.S. Department of Education, Institute of Education Sciences, National Center for Education Evaluation and Regional Assistance, Regional Educational Laboratory Appalachia.

Sawchuk, S. (2020, August 26). Overcoming Covid-19 learning loss. Education Week, 40 (2), 6.

This blog was developed with support from Arnold Ventures. The views expressed here do not necessarily reflect those of Arnold Ventures.Note: If you would like to subscribe to Robert Slavin’s weekly blogs, just send your email address to thebee@bestevidence.org