This paper, written by Robert Slavin and colleagues from Johns Hopkins University, the University of Liege and the Institute for Effective Education, reviews research on the outcomes of writing interventions for pupils in Years 3 to 13. Studies had to meet rigorous standards of research including use of randomised or well-matched control groups; measures independent of the programme developers, researchers and teachers; and adequate sample size and duration. Fourteen studies of 12 programmes met the criteria and programmes were divided into three categories: writing process models, cooperative learning writing programmes, and programmes integrating reading and writing.
Pupil achievement effects on writing were positive in all categories, with an effect size of +0.18 across all 14 studies. Similar outcomes were found for writing programmes that focused on the writing process (effect size = +0.17), those using cooperative learning (effect size = +0.16), and those focusing on interactions between reading and writing (effect size = +0.19).
Source: A quantitative synthesis of research on writing approaches in Years 3 to 13 (July 2019), Education Endowment Foundation