C27 Homework and achievement
narrowed 1 attack: 1 narrowed · serves Q1 · last change 4 November 2026
Assigned homework goes with higher achievement, and in correlational studies the link is clearly stronger for pupils in grades 7–12 than in grades K–6, where it is small; but the small early-grade link has not been shown to mean a small effect: in the few experiments, classes given homework scored higher than classes without it, and in a systematic review whose homework-versus-none experiments were mostly in grades 3–6 (6 of 10; 4 in grades 7–12) the gain was about 0.45 standard deviations (mostly old studies at moderate to critical risk of bias; Guo et al. 2024).
Go deeper
Where it holds
All limits (6)
Inside the circle: the core of the claim. Outside: every bound and carve-out in the claim file, numbered, with the attack that forced or added it where the record shows one.
forced by a narrowing attackin the original wordingwritten at creation, or added without a narrowing
Warm cards in the list were added by later attacks; plain cards were in the original draft or written at creation.
Assigned homework and achievement; most evidence is correlational, and the size depends on how homework is measured (students' own reports gave stronger links).
Written when the claim was created (29 October 2026); not forced by an attack
Evidence on file: Cooper, Robinson & Patall 2006 (Review of Educational Research, DOI 10.3102/00346543076001001; full text): generally consistent positive influence across designs; correlations stronger in grades 7–12 than K–6; five experiments with usable effects gave a mean d ≈ .60 on unit tests (95% CI about .38–.82), with design and unit-of-analysis limits.
Written when the claim was created (29 October 2026); not forced by an attack
Fan, Xu, Cai, He & Fan 2017 (Educational Research Review 20, DOI 10.1016/j.edurev.2016.11.003; abstract/secondary summary only, flagged): maths and science r ≈ .22; numbers must be checked in the paper before any ledger use.
Written when the claim was created (29 October 2026); not forced by an attack
Weakened 2026-11-03 (nightly attack): Guo, Li, Xu, Hu, Liu, Xing, Li, White & Yang 2024 (Campbell Systematic Reviews 20(3), e1431, DOI 10.1002/cl2.1431; open access, full text read): 11 controlled studies of homework versus no homework (2 RCTs, both at high risk of bias; 9 non-randomised, 4 moderate, 2 serious and 3 critical risk of bias; most published 1939–1995; only one with a follow-up); pooled g = 0.45 (95% CI 0.24–0.66; 14 comparisons; I² = 71%), arithmetic computation g = 0.46, problem solving g = 0.17, concepts not significant; the 14 homework-versus-none comparisons come from 10 studies published 1939–1995 in grades 3 (2 studies), 4–6 (1), 5 (1), 6 (2), 7 (1; Foran & Weber 1939), 8 (1; Ewart Anderson 1946) and senior high-school English (2; McGrath 1992, Tupesis 1972), so 6 of 10 in grades 3–6 and 4 in grades 7–12; the grade-2 randomised trial (Dolean & Lervåg 2021), the only study with a follow-up, compared more with less homework and is not in the pooled g; no grade-level subgroup analysis was possible (corrected 2026-11-04 against Table 2 and §5.3.1; the earlier "of the 8 studies that reported grade, 7 were in grades 2–6 and 1 in grade 8" was wrong).
Forced by attack #1 · Guo, Li, Xu, Hu, Liu, Xing, Li, White & Yang 2024 · 3 November 2026
Wording changed later: Added with attack #2 (corrected; it did not narrow the claim) · Guo, Li, Xu, Hu, Liu, Xing, Li, White & Yang 2024 · 4 November 2026.
The review's RCT labels differ between §5.2.1 and Table 2; Egger's test p = 0.06.
Added with attack #2 (corrected; it did not narrow the claim) · Guo, Li, Xu, Hu, Liu, Xing, Li, White & Yang 2024 · 4 November 2026
So the grade 7–12 versus K–6 contrast rests on correlations; the experimental evidence, though weak, is mostly from primary school and does not show a small effect there.
Forced by attack #1 · Guo, Li, Xu, Hu, Liu, Xing, Li, White & Yang 2024 · 3 November 2026
2 of 6 bounds and carve-outs were forced by a specific attack.
How it changed
The ledger records 1 attack (and 1 correction to our notes), but no earlier wording of C27 is on record, so the text cannot be replayed step by step. Only the current wording is shown.
Assigned homework goes with higher achievement, and in correlational studies the link is clearly stronger for pupils in grades 7–12 than in grades K–6, where it is small; but the small early-grade link has not been shown to mean a small effect: in the few experiments, classes given homework scored higher than classes without it, and in a systematic review whose homework-versus-none experiments were mostly in grades 3–6 (6 of 10; 4 in grades 7–12) the gain was about 0.45 standard deviations (mostly old studies at moderate to critical risk of bias; Guo et al. 2024).
What would change this
What would kill it: A meta-analysis finds no positive link between homework and achievement overall, or a link no stronger in grades 7–12 than in grades K–6, or a well-controlled trial finds that adding homework does not raise test results. Added as a claim on 29 October 2026, promoted from a candidate belief in the evidence library.
Attack record
1 attack: 1 narrowed. Counts of attacks, not a score.
Full attack list (1)
- #1 narrowed 3 November 2026 · Guo, Li, Xu, Hu, Liu, Xing, Li, White & Yang 2024 · target: claim-text
"Where it is small" for grades K–6 rests on correlations; the controlled experiments of homework versus no homework are mostly in primary school and show a sizeable gain, so the claim's grade contrast does not hold as a statement about effects.
Strongest reading and verdict reasoning
Steelmans to: The strongest version: the only causal evidence in a recent Campbell review (11 controlled studies, homework vs none, g = 0.45) comes mostly from grades 2–6, so the claim's "small" for K–6 reflects correlational designs, not what happens when homework is added.
Why: Nightly-attacks run of 2026-11-03 Europe/Stockholm. Pooled g = 0.45 (95% CI 0.24–0.66; 14 comparisons; I² = 71%); arithmetic computation g = 0.46, problem solving g = 0.17, concepts not significant. Of the 8 studies that reported grade: grade 2 (one), 3 (two), 5 (one), 6 (two), 4–6 (one), 8 (one); no grade subgroup analysis was possible. Weak evidence: 2 RCTs both at high risk of bias, 9 non-randomised studies (4 moderate, 2 serious, 3 critical risk of bias), mostly 1939–1995, one with follow-up. Not a kill: the correlational grade contrast (Cooper et al. 2006) stands, and the review does not show a link no stronger in grades 7–12. Kill-match check: the new hedge ("has not been shown to mean a small effect") does not empty the kill line; "a link no stronger in grades 7–12 than in grades K–6" and "a well-controlled trial finds adding homework does not raise test results" still name results the new text does not concede. Not a kill-mismatch.
Corrections to our notes
These fix a number or a fact in our notes. They are not attacks and do not count toward the floor of 3 survivals.
- — C27's claim text says the review's experiments were "mostly in grades 2–6" and its limits say "of the 8 studies that reported grade, 7 were in grades 2–6 and 1 in grade 8"; the review's Table 2 and §5.3.1 show that the pooled homework-versus-none g = 0.45 comes from 10 studies, 6 in grades 3–6 and 4 in grades 7–12, and that the grade-2 RCT is not in the pooled estimate.
Details
What was checked: claim-text grade description and Bounds grade count (not a kill-condition test).
Why: Nightly-attacks run of 2026-11-04 Europe/Stockholm. Re-checked tonight in the stored full text: "Ten studies with 14 independent reports compared the effectiveness of homework with no-homework treatment" (§5.3.1); Table 2 grades: Maertens 1969 grade 3, Townsend 1995 grade 3, Maertens & Johnston 1972 grades 4–6, Foyle 1990 grade 5, Koch 1965 grade 6, Gray & Allison 1971 grade 6, Foran & Weber 1939 grade 7 (292 pupils), Ewart Anderson 1946 grade 8 (58), McGrath 1992 and Tupesis 1972 senior high-school English; Dolean & Lervåg 2021 (grade 2, RCT, the only follow-up) compared more vs less homework. The 2026-11-03 weaken's logic stands (the experiments do not show a small effect in primary school; 6 of 10 are primary), so this is a correction, not a narrowing. Status stays weakened. Not a survival; streak unaffected.
Evidence
4 linked sources: 2 supports, 2 limits (first-pass draft, pending human review). supports: Cooper et al. 2006, Fan et al. 2017 · limits: Qin & Wang 2026, Guo et al. 2024