---
title: "Does Quizzing Boost Learning? Meta-Analysis (Yang 2021)"
description: "Meta-analysis of 222 classroom studies and 48,478 students: quizzing raised achievement by a medium amount (g = 0.50) versus other strategies."
canonical: https://research.askpoppy.ai/papers/yang-2021-testing-boosts-classroom-learning-meta-analysis/
last_updated: 2026-10-21
---

[Retrieval practice (the testing effect)](/topics/retrieval-practice/)

# Quizzing boosts classroom learning: a meta-analysis of 222 studies

**In short:** Across 222 studies in real classrooms with 48,478 students, low-stakes quizzing improved achievement by a medium amount compared with restudying and other strategies. Feedback, repeated quizzes and quiz questions that match the final test all changed how big the benefit was.

|  |  |
| --- | --- |
| Paper | [Testing (quizzing) boosts classroom learning: A systematic and meta-analytic review](https://doi.org/10.1037/bul0000309) |
| Authors | Chunliang Yang, Liang Luo, Miguel A. Vadillo, Rongjun Yu, David R. Shanks |
| Published | April 2021 · Psychological Bulletin 147(4), 399–435 |
| Study type | Systematic review and meta-analysis · Peer-reviewed |
| What we read | Abstract only. Summary based on the published abstract only. |
| Summarized | 21 October 2026 |

## What they did

The authors pooled data from 222 independent classroom studies of the "testing effect" and analysed what made the effect larger or smaller.

## Who took part

48,478 students across the included studies.

## What they found

- Quizzing raised academic achievement by a medium amount overall.
- The size of the benefit depended on what it was compared with, whether quiz and final test formats matched, whether the material matched, corrective feedback, number of quiz repetitions, where and when quizzes were given, how long the treatment lasted and the study design.
- The authors see support for three explanations: extra exposure to the material, practising the kind of thinking the test needs, and motivation.

**Effect size:** Overall g = 0.499.

## Limitations

- A meta-analysis is only as good as the studies it pools, and studies varied a lot.
- We read only the abstract, so we don't report the size of each moderator here.

## What this means for learners and parents

- Short, low-stakes quizzes beat rereading notes. That holds in classrooms, not only labs.
- Check answers after quizzing, and quiz more than once.
- At home: turn notes into questions and answer them before looking.

## Put it into practice (free tools)

- [Make flashcards from your notes and quiz yourself](https://learn.askpoppy.ai/recall/)
- [The blurting method](https://learn.askpoppy.ai/blurt/)

## Citation

Chunliang Yang, Liang Luo, Miguel A. Vadillo, Rongjun Yu, David R. Shanks (2021). Testing (quizzing) boosts classroom learning: A systematic and meta-analytic review. *Psychological Bulletin 147(4), 399–435*. <https://doi.org/10.1037/bul0000309>

## Related summaries

- [The classic study: testing yourself beats rereading after a week](/papers/roediger-karpicke-2006-test-enhanced-learning/) · Henry L. Roediger III et al., 2006 · Lab experiments

Summary by the Ask Poppy team, AI-assisted and checked against the paper. Summarized 21 October 2026. Spotted an error? [simon@askpoppy.ai](mailto:simon@askpoppy.ai) · [Editorial policy](/about/)

```json
{"@context": "https://schema.org", "@type": "Article", "headline": "Does Quizzing Boost Learning? Meta-Analysis (Yang 2021)", "alternativeHeadline": "Quizzing boosts classroom learning: a meta-analysis of 222 studies", "description": "Meta-analysis of 222 classroom studies and 48,478 students: quizzing raised achievement by a medium amount (g = 0.50) versus other strategies.", "url": "https://research.askpoppy.ai/papers/yang-2021-testing-boosts-classroom-learning-meta-analysis/", "mainEntityOfPage": "https://research.askpoppy.ai/papers/yang-2021-testing-boosts-classroom-learning-meta-analysis/", "author": {"@type": "Organization", "name": "Ask Poppy team", "url": "https://research.askpoppy.ai/about/", "parentOrganization": {"@id": "https://askpoppy.ai/#org"}}, "publisher": {"@id": "https://askpoppy.ai/#org"}, "datePublished": "2026-10-21", "dateModified": "2026-10-21", "inLanguage": "en", "about": [{"@id": "https://doi.org/10.1037/bul0000309"}, {"@type": "Thing", "name": "Retrieval practice (the testing effect)"}], "citation": {"@id": "https://doi.org/10.1037/bul0000309"}, "isBasedOn": "https://doi.org/10.1037/bul0000309", "image": "https://research.askpoppy.ai/og/yang-2021-testing-boosts-classroom-learning-meta-analysis.png", "isAccessibleForFree": true}
{"@context": "https://schema.org", "@type": "ScholarlyArticle", "@id": "https://doi.org/10.1037/bul0000309", "headline": "Testing (quizzing) boosts classroom learning: A systematic and meta-analytic review", "name": "Testing (quizzing) boosts classroom learning: A systematic and meta-analytic review", "author": [{"@type": "Person", "name": "Chunliang Yang"}, {"@type": "Person", "name": "Liang Luo"}, {"@type": "Person", "name": "Miguel A. Vadillo"}, {"@type": "Person", "name": "Rongjun Yu"}, {"@type": "Person", "name": "David R. Shanks"}], "datePublished": "2021-04", "isPartOf": {"@type": "Periodical", "name": "Psychological Bulletin"}, "identifier": {"@type": "PropertyValue", "propertyID": "DOI", "value": "10.1037/bul0000309"}, "sameAs": "https://doi.org/10.1037/bul0000309", "url": "https://doi.org/10.1037/bul0000309"}
{"@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [{"@type": "ListItem", "position": 1, "name": "Home", "item": "https://research.askpoppy.ai/"}, {"@type": "ListItem", "position": 2, "name": "Summaries", "item": "https://research.askpoppy.ai/papers/"}, {"@type": "ListItem", "position": 3, "name": "Does Quizzing Boost Learning? Meta-Analysis (Yan", "item": "https://research.askpoppy.ai/papers/yang-2021-testing-boosts-classroom-learning-meta-analysis/"}]}
{"@context": "https://schema.org", "@type": "Organization", "@id": "https://askpoppy.ai/#org", "name": "Ask Poppy", "legalName": "Poppy Labs AS", "url": "https://askpoppy.ai/", "logo": "https://askpoppy.ai/poppy-mark.png", "email": "hello@askpoppy.ai", "foundingLocation": "Oslo, Norway", "address": {"@type": "PostalAddress", "addressLocality": "Oslo", "addressCountry": "NO"}, "founder": {"@type": "Person", "name": "Simon Dreyer"}}
```