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Cited by 461Education during COVID-19 pandemicCOVID-19 Pandemic ImpactsSchool Choice and Performance

Effects of COVID-19-Related School Closures on Student Achievement-A Systematic Review

Open access
Hammerstein, Svenja, König, Christoph, Dreisörner, Thomas, Frey, Andreas·2021·Frontiers in Psychology
DOI 10.3389/fpsyg.2021.746289PMC PMC8481663

Published version of a preprint

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Abstract

The COVID-19 pandemic led to numerous governments deciding to close schools for several weeks in spring 2020. Empirical evidence on the impact of COVID-19-related school closures on academic achievement is only just emerging. The present work aimed to provide a first systematic overview of evidence-based studies on general and differential effects of COVID-19-related school closures in spring 2020 on student achievement in primary and secondary education. Results indicate a negative effect of school closures on student achievement, specifically in younger students and students from families with low socioeconomic status. Moreover, certain measures can be identified that might mitigate these negative effects. The findings are discussed in the context of their possible consequences for national educational policies when facing future school closures.

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review synthesizes 11 studies on COVID-19-related school closures in spring 2020 and finds mostly negative effects on student achievement, with a median effect of −0.08 SD. Negative effects were especially pronounced for younger students and students from low socioeconomic status families, while some online-learning software studies reported positive effects.

Key findings

  • Across included studies, effects ranged from −0.37 SD to +0.25 SD, with a median of −0.08 SD; median effects were −0.10 SD for mathematics and −0.09 SD for reading.
  • Seven studies reported negative effects on mathematics, five on reading, and two on other subjects such as science.
  • Differential effects: younger children were more negatively affected than older children (−0.37 SD vs. −0.10 SD; Tomasik et al., 2020), and low-SES students were more affected, with one study reporting +60% learning loss in low-SES students (Engzell et al., 2021).
  • Three studies using online-learning software reported positive effects (+0.20 SD in Meeter, +0.25 SD for correct solutions to open questions in van der Velde et al., and improved mathematics performance in Spitzer and Musslick).

Methods

  • Systematic review following PRISMA; searched Web of Science from March 1, 2020 to April 30, 2021, plus preprint servers PsyArXiv, EdArXiv, and SocArXiv, yielding 601 potentially relevant studies.
  • Inclusion required a focus on COVID-19-related school closures, primary/secondary education, student achievement/test scores as dependent variable, actual data collected prior to and during/after closures, statistical analyses, and reported effect sizes; final inclusion was 9 studies plus 2 from backward reference searching (11 total).
  • Risk of bias assessed with ROBINS-I; synthesis extracted country, closure duration, sample, subjects, statistical method, general effects, and differential effects, converting effects to SD where possible and calculating medians; meta-analytic models were not feasible due to the small number of studies.

Limitations

  • The paper states that evidence is available for only a small number of countries, clustered around developed countries, with no studies from developing countries yet.
  • The paper states that the original studies were not designed to identify reasons for the differential effects, so additional studies are required to explain them exhaustively.
  • The paper states that the highest risk of bias was due to lack of inclusion of potential confounding variables (ROBINS-I Domain 1), and that the small number of studies prevented random- or mixed-effects meta-analytic models.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3389/fpsyg.2021.746289

Cites

40 of 41 references verified0 citation errors · 1 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

15 of 39 cited sources checked · 10 supported · 0 flagged · accuracy not yet measured

  • Findingcitation

    van der Velde et al. (2021) reported an increase in correct solutions on open questions within a French learning program.

    “Similarly, van der Velde et al. (2021) reported an increase in correct solutions on open questions within a French learning program.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites van der Velde et al., 2021 source
  • Interpretationcitation

    With the possibility to adapt assignments in online programs individually, low-performing children might have been addressed more thoroughly according to their needs.

    “Finally, with the possibility to adapt the assignments in online programs individually to the students, low-performing children might have been addressed more thoroughly according to their needs (Spitzer and Musslick, 2021).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Spitzer and Musslick, 2021 source
  • Interpretationcitation

    Low-performing students might be less distracted in comparison to learning in a classroom setting.

    “Additionally, low-performing students might be less distracted in comparison to learning in a classroom setting (Spitzer and Musslick, 2021).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Spitzer and Musslick, 2021 source
  • Findingcitation

    Children from families with low SES were more affected than children from families with high SES (Maldonado and De Witte, 2020; Engzell et al., 2021).

    “Second, children from families with a low socioeconomic status (SES) were more affected than children from families with a high SES were (Maldonado and De Witte, 2020; Engzell et al., 2021).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Maldonado and De Witte, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Engzell et al., 2021 source
  • Findingcitation

    Low-performing students benefited more from systematic online-learning methods (Clark et al., 2020; Spitzer and Musslick, 2021).

    “Finally, low-performing students benefited more from systematic online-learning methods (Clark et al., 2020; Spitzer and Musslick, 2021).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Clark et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Spitzer and Musslick, 2021 source
  • May combine two claims. 17
  • Classified as probably not a substantial claim. 15

  • May combine two claims.

    Interpretationcitation

    Students increased time using online-learning software at home, were less distracted or experienced less time pressure in home-schooling, or were presented with individualized assignments.

    “Moreover, students increased the time using the online-learning software at home, were less distracted or experienced less time pressure in a home-schooling rather than classroom setting, or were presented with individualized assignments within the online program (see also Meeter, 2021; Spitzer and Musslick, 2021; van der Velde et al., 2021).”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites Meeter, 2021

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Spitzer and Musslick, 2021 source

      The Introduction reports increased software use during school closures, but measures this as three times more students using it, not more time spent per student. The Discussion proposes reduced distraction at home and individualized problem sets as possible explanations, rather than established findings. It does not identify reduced time pressure as a factor. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites van der Velde et al., 2021 source

      The Discussion reports increased use of the online retrieval-practice tool during lockdown. It says higher accuracy and response times on open-answer questions *perhaps* indicated less time pressure or better focus at home; it does not establish that students were less distracted. The Data Set section describes an adaptive tool, but does not say students were given individualized assignments. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingcitation

    Two studies found positive effects on student achievement in mathematics and reading (Gore et al., 2021), or in reading only (Depping et al., 2021).

    “Additionally, two studies found positive effects on student achievement in mathematics and reading (Gore et al., 2021), or in reading only (Depping et al., 2021).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Gore et al., 2021 source

      The Results sections on student achievement and location report additional mathematics growth for Year 3 students in mid-ICSEA schools and additional reading growth in specific location subgroups. But neither Year 3 nor Year 4 showed an overall difference from the 2019 cohort, and low-ICSEA Year 3 students had less mathematics growth. The claim omits these subgroup limits and implies broadly positive effects in both subjects. (LLM, conf=0.89)

      Experimental — accuracy not yet measured
    • cites Depping et al., 2021 source

  • May combine two claims.

    Findingcitation

    One study reported an interaction between grade and SES: for younger children from schools with low school-level SES, learning losses of 0.16 SD were found, while younger children from schools with medium school-level SES experienced learning gains of 0.15 SD (Gore et al., 2021).

    “In this context, one study reported an interaction between grade and SES, that is, for younger children from schools with low school-level SES, learning losses of 0.16 SD were found, while younger children from schools with medium school-level SES experienced learning gains of 0.15 SD (Gore et al., 2021).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Gore et al., 2021 source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The review was organized following the PRISMA reporting guidelines.

    “The review is organized following the reporting guidelines of the PRISMA statement (Page et al., 2021)”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Page et al., 2021 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Haeck and Lefebvre (2020) estimated that socioeconomic achievement gaps would increase by up to 30%.

    “Moreover, Haeck and Lefebvre (2020) estimated that socioeconomic achievement gaps would increase by up to 30%.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Haeck and Lefebvre, 2020 source

  • May combine two claims.

    Findingcitation

    Low-performing students were more affected by COVID-19-related school closures in mathematics, while high-performing students were more affected in reading (Schult et al., 2021).

    “Third, low-performing students were more affected by COVID-19-related school closures in mathematics, while high-performing students were more affected by COVID-19-related school closures in reading (Schult et al., 2021).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Schult et al., 2021 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    Reasons for finding larger learning losses in mathematics than in reading might be that students spent more time on reading during school closures and that supporting children in reading skills might have been easier for parents than supporting mathematics.

    “On the other hand, reasons for finding larger learning losses in mathematics than in reading might be that students spent more time on reading during school closures and that supporting children in their reading skills might have been easier to realize for parents than supporting children in improving their competencies in mathematics (e.g., Depping et al., 2021; Schult et al., 2021).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Depping et al., 2021 source
    • cites Schult et al., 2021 source

      Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The Cochrane Risk Assessment was conducted independently by the first and second author using ROBINS-I.

    “The Cochrane Risk Assessment of the included studies was conducted independently by the first and second author using the “Risk Of Bias in Non-Randomized Studies of Interventions” tool (ROBINS-I; Sterne et al., 2016).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Sterne et al., 2016 source

  • May combine two claims.

    Findingown data

    The median effect on mathematics was d = −0.10 SD and on reading was −0.09 SD.

    “Even though the median for the effect on mathematics and reading is comparable when averaging above all studies (d = −0.10 SD and−0.09 SD for mathematics and reading, respectively)”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Woessmann (2020) estimated a negative effect of 0.10 SD on student achievement due to COVID-19-related school closures.

    “For instance, Woessmann (2020) estimated a negative effect of 0.10 SD on student achievement due to COVID-19-related school closures.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Woessmann, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    Many students might not speak the language in which they are tested at home, hence not benefitting much in their language skills during school closures.

    “As another explanation, many students might not speak the language in which they are tested in at home, hence, not benefitting much in their language skills during school closures (e.g., Maldonado and De Witte, 2020).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Maldonado and De Witte, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Study design and conductown data

    Bias due to missing data, measurement of outcomes, or selection of reported results is unlikely, as most studies exhibited very small proportions of missing data (except Depping et al., 2021), and were highly transparent in their reporting of the results (except, partially, van der Velde et al., 2021).

    “Lastly, bias due to missing data, measurement of outcomes, or selection of reported results is unlikely, as most studies exhibited very small proportions of missing data (except Depping et al., 2021), and were highly transparent in their reporting of the results (except, partially, van der Velde et al., 2021, who only report significant mean differences between groups in sufficient detail).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The proportion of students enrolled in primary or secondary education is considerably smaller in poorer countries.

    “Nevertheless, the proportion of students enrolled in primary or secondary education is considerably smaller in poorer countries (Ward, 2020).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Ward, 2020 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    A randomly selected subset of 20 studies was evaluated by both the authors and the research assistants to determine rater agreement.

    “To determine the degree of rater agreement on the selection of the studies, a randomly selected subset of 20 studies was evaluated by both the authors and the research assistants.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    The differential effect on low-performing and high-performing students may be due to high-performing students being capable of improving their performance regardless of the learning environment, while low-performing students specifically benefit from systematic online learning.

    “The differential effect on low-performing and high-performing students may be due to high-performing students being capable of improving their performance regardless of the learning environment, while low-performing students specifically benefit from systematic online learning (Clark et al., 2020).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Clark et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation

    The reported effects are comparable in size to findings of research on summer losses (d = −0.005 SD to −0.05 SD per week) and comparable to Woessmann's initial estimate.

    “The reported effects are comparable in size to findings of research on summer losses (d = −0.005 SD to −0.05 SD per week; see also Kuhfeld et al., 2020a) and comparable to Woessmann's initial estimate.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Kuhfeld et al., 2020a

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Woessmann, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation

    Summer losses are d = −0.005 SD to −0.05 SD per week.

    “The reported effects are comparable in size to findings of research on summer losses (d = −0.005 SD to −0.05 SD per week; see also Kuhfeld et al., 2020a)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Kuhfeld et al., 2020a

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationnone given

    The number of countries for which evidence of these effects is available is still small and clustered around developed countries; studies from developing countries are not available yet.

    “It has to be noted that the number of countries for which evidence of these effects are available is still small, and clustered around developed countries. Especially studies from developing countries are not available yet.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationreasoning

    Additional learning losses are likely due to the cumulative nature of learning processes and student achievement.

    “Due to the cumulative nature of learning processes and student achievement, additional learning losses are likely.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The first COVID-19-related school closures in spring 2020 were followed by similar measures in the fall and winter of 2020/2021.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductreasoning

    Studies were required to have collected actual data prior to and during/after COVID-19-related school closures and to have applied statistical analyses and report an effect size.

    “Studies were required (1) to have collected actual data prior to and during/after COVID-19-related school closures, and (2) to have applied statistical analyses and to report an effect size.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Most remote learning measures implemented during the first school closures in spring 2020 were not effective for student learning; there was no difference between them and the absence of systematic teaching during summer vacation.

    “This indicates that most remote learning measures implemented during the first school closures in spring 2020 were not effective for student learning; there was no difference between them and the absence of systematic teaching during summer vacation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    The reasons for students from low SES families being more affected relate to access to remote learning, their learning behavior, and the support provided from families and schools.

    “The reasons for students from low SES families being more affected relate to access to remote learning, their learning behavior, and the support provided from families and schools.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    A learning loss of up to 38 points on the PISA scale is estimated, corresponding to an effect size of 0.38 or 0.9 school years.

    “A learning loss of up to 38 points on the Programme for International Student Assessment (PISA1) scale is estimated, which corresponds to an effect size (Cohen's d) of 0.38 or 0.9 school years (Azevedo et al., 2020; Kuhfeld et al., 2020a; Wyse et al., 2020; Kaffenberger, 2021).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Azevedo et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Kuhfeld et al., 2020a

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Wyse et al., 2020 source

  • May combine two claims.

    Premisecitation

    Children from families with low SES are less likely to have access to remote learning, are less often provided with active learning assistance from their schools, and spend less time on learning than children from families with high SES.

    “Children from families with a low SES are less likely to have access to remote learning (UNESCO, 2021), are less often provided with active learning assistance from their schools (Tomasik et al., 2020), and spend less time on learning (Meeter, 2021) than children from families with a high SES.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites UNESCO, 2021

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Tomasik et al., 2020 source
    • cites Meeter, 2021

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation

    The positive effects on mathematics and reading in two studies might be accounted for by achievement measurement being timed some months after school closures and effective compensatory measures being implemented.

    “This result might be accounted for by the achievement measurement being timed some months after school closures in both studies and the possibility of effective compensatory measures being implemented by teachers, schools, and local policy makers during this time to counteract learning losses, such as offering learning groups during summer vacation in parts of Germany (Depping et al., 2021).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Depping et al., 2021 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    Reasons for finding larger learning losses in reading than in mathematics might be that mathematics is easier to teach in distance learning, as it is simple to provide exercises and tests digitally or as worksheets.

    “On the one hand, reasons for finding larger learning losses in reading than in mathematics might be that “mathematics is easier to teach in distance learning, as it is simple to provide exercises and tests digitally or as worksheets” (Maldonado and De Witte, 2020, p. 13).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Maldonado and De Witte, 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The reduction in in-person learning was smaller for low-income countries than for medium-income countries.

    “We know, however, that the reduction in in-person learning was smaller for low-income countries than for medium-income countries (UNESCO, 2021).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites UNESCO, 2021

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

27 of 27

  • The authors state this as an assumption.

    In spring 2020, the ad hoc implementation of online teaching gave students, teachers, schools, and parents little time to prepare for or adapt to measures of remote learning.

    “the assumption that, in spring 2020, the ad hoc implementation of online teaching gave students, teachers, schools, and parents little time to prepare for or adapt to measures of remote learning.”

  • The paper relies on this without support.

    COVID-19 related school closures were not intended interventions.

    “This is because the COVID-19 related school closures were not intended interventions.”

  • The paper relies on this without support.

    The first COVID-19-related school closures in spring 2020 were followed by similar measures in the fall and winter of 2020/2021.

    “The first COVID-19-related school closures in spring 2020 were followed by similar measures in the fall and winter of 2020/2021.”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Systematic reviews and meta-analyses suggest an average learning loss attributable to COVID-19 school closures of 0.17 of a standard deviation, at least one-third of a year's worth of learning.

    “Nevertheless, there are several systematic reviews and meta-analyses, and these suggest an average learning loss attributable to COVID-19 school closures of 0.17 of a standard deviation—that is, at least one-third of a year’s worth of learning16–20.”

    From COVID-19, school closures, and student learning outcomes. New global evidence from PISA (2025) · cites this paper as [18]

    The Results (General Effects; page not provided) report that most included studies found learning losses after COVID-19 school closures. But the review reports a median effect of −0.08 SD, not an average of −0.17 SD, and does not equate its findings to at least one-third of a year's learning. The Method (Synthesis; page not provided) also says a meta-analysis was not feasible. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • The results confirm the core conclusion of prior synthesizing research examining the first phase of school closures.

    “The results confirm the core conclusion of prior synthesizing research examining the first phase school closures.”

    From The Impact of COVID‐19‐Related School Closures on Student Achievement—A Meta‐Analysis (2022) · cites this paper as Hammerstein et al., 2021

  • The study's results are similar to what systematic reviews are finding.

    “Interestingly, our results are similar to what systematic reviews are finding learning16–20,44,45.”

    From COVID-19, school closures, and student learning outcomes. New global evidence from PISA (2025) · cites this paper as [18]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Engzell study credited with a result in a subject not listed in Table 1

    Minor

    The results section counts Engzell et al. among studies reporting a negative effect in other subjects, such as science, but Table 1 lists only reading and mathematics for that study.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. 2021, What's Next? Lessons on Education Recovery

Cited by

Sorted by citations

Related

Authors
Hammerstein, S., König, C., Dreisörner, T., & Frey, A.
Affiliations
Goethe University Frankfurt (DE)
Corresponding author
Hammerstein, Svenja
ORCID
Venue
Frontiers in Psychology
Publisher
Frontiers Media SA
Published
2021-09-16
Volume
12
Pages
746289-746289
ISSN
1664-1078 (ISSN-L)
DOI
10.3389/fpsyg.2021.746289
PMC
PMC8481663
OpenAlex
W3172046965
Semantic Scholar
650bd6b2e0b8178e55d72195ab3ccad79308a63f
Cited by
461
References
38
Citations by year
2026: 32 · 2025: 66 · 2024: 109 · 2023: 155 · 2022: 114 · 2021: 14
FWCI
26.84
Type
journal article
Language
en
Open access
Licence
Locations
  • Frontiers in Psychology (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • OSF Preprints (OSF Preprints) (acceptedVersion)
  • NORA - Norwegian Open Research Archives (submittedVersion, cc-by)
  • Europe PMC (PubMed Central) (submittedVersion, other-oa)
  • PubMed Central (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Publication Server of Goethe University Frankfurt am Main (Goethe University Frankfurt) (submittedVersion, cc-by)
  • PsyArXiv (OSF Preprints) (submittedVersion)
Topics
  • Social Sciences › Education › Education during COVID-19 pandemic
  • Social Sciences › Economics, Econometrics and Finance › Economics and Econometrics › COVID-19 Pandemic Impacts
  • Social Sciences › Education › School Choice and Performance
Keywords
COVID-19 pandemic, school closures, academic performance, primary education, secondary education, socioeconomic status, low-income students, younger students

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Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-07.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-07.

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Statistics and arithmetic are recomputed, not judged.

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