Table 3 Results of the meta-analyses on the effectiveness of the 3 categories of educational interventions

Composite test scores (SMD±SE)

Provision of instructional materials vs no intervention (business as usual)

Not statistically significant:

SMD: 0.01±0.01, 95% CI [-0.01;0.02] (p = 0.23) ^a

5 effect sizes from 3 studies ^b

Snilstveit, 2015 [23]

Language arts test scores (SMD±SE)

Provision of instructional materials vs no intervention (business as usual)

Not statistically significant:

SMD: 0.00±0.01, 95% CI [-0.02;0.02] (p = 0.78) ^a

5 effect sizes from 4 studies ^b

Snilstveit, 2015 [23]

Maths test scores (SMD±SE)

Provision of instructional materials vs no intervention (business as usual)

Not statistically significant:

SMD: -0.02±0.02, 95% CI [-0.06;0.02] (p = 0.26) ^a

5 effect sizes from 4 studies ^b

Snilstveit, 2015 [23]

Learning/testing outcomes (Cohen’s d ± SE)

Use of alternative pedagogical methods vs conventional teaching methods

Statistically significant:

Cohen’s d: 0.918±0.314, 95% CI [0.25;1.59] (p<0.05)

41 effect sizes from 17 studies ^b

Conn, 2014 [24]

Cognitive test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Not statistically significant:

SMD: 0.01±0.03, 95% CI

[-0.04;0.07] (p = 0.66) ^a

2 effect sizes from 2 studies ^b

Snilstveit, 2015 [23]

Composite test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Statistically significant:

SMD: 0.06±0.01, 95% CI [0.03;0.08] (p < 0.0001)

3 effect sizes from 3 studies ^b

Snilstveit, 2015 [23]

Composite test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Grades 1-3 sub-group:

Statistically significant:

SMD: 0.09±0.02, 95% CI [0.05;0.13] (p < 0.0001)

2 effect sizes from 2 studies ^b

Snilstveit, 2015 [23]

Composite test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Grades 4-5 sub-group:

Statistically significant:

SMD: 0.08±0.02, 95% CI [0.04;0.12] (p < 0.0001)

2 effect sizes from 2 studies ^b

Snilstveit, 2015 [23]

Language arts test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Statistically significant:

SMD: 0.23±0.05, 95% CI [0.13;0.34] (p < 0.001)

67 effect sizes from 17 studies ^b

Snilstveit, 2015 [23]

Language arts test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Grades 1-3 sub-group:

Statistically significant:

SMD: 0.23±0.06, 95% CI [0.11;0.35] (p < 0.01)

63 effect sizes from 14 studies ^b

Snilstveit, 2015 [23]

Language arts test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Grades 4-6 sub-group:

Not statistically significant:

SMD: 0.21±0.13, 95% CI [-0.04;0.47] (p = 0.10) ^a

4 effect sizes from 4 studies ^b

Snilstveit, 2015 [23]

Maths test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Statistically significant:

SMD: 0.14±0.03, 95% CI [0.08;0.20] (p < 0.001)

24 effect sizes from 14 studies ^b

Snilstveit, 2015 [23]

Maths test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Grades 1-3 sub-group:

Statistically significant:

SMD: 0.08±0.03, 95% CI [0.03;0.13] (p < 0.01)

9 effect sizes from 9 studies ^b

Snilstveit, 2015 [23]

Maths test scores (SMD±SE)

Structured pedagogy interventionsvs no intervention or other small educational intervention

Grades 4-6 sub-group:

Statistically significant:

SMD: 0.21±0.08, 95% CI [0.04;0.37] (p < 0.05)

4 effect sizes from 4 studies ^b

Snilstveit, 2015 [23]