A meta-analysis of writing instruction for students in the elementary grades.

In an effort to identify effective instructional practices for teaching writing to elementary grade students, we conducted a meta-analysis of the writing intervention literature, focusing our efforts on true and quasi-experiments. We located 115 documents that included the statistics for computing an effect size (ES). We calculated an average weighted ES for 13 writing interventions. To be included in the analysis, a writing intervention had to be tested in 4 studies. Six writing interventions involved explicitly teaching writing processes, skills, or knowledge. All but 1 of these interventions (grammar instruction) produced a statistically significant effect: strategy instruction (ES = 1.02), adding…