Published journal version

Virtual communication holds the promise of enabling low-cost professional development at scale, but the benefits of in-person interaction might be difficult to replicate. We report on an experiment in South Africa comparing on-site with virtual coaching of public primary school teachers. After three years, on-site coaching improved students' English oral language and reading proficiency (0.31 and 0.13 SD, respectively). Virtual coaching had a smaller impact on English oral language proficiency (0.12 SD), no impact on English reading proficiency, and an unintended negative effect on home language literacy. Classroom observations show that on-site coaching improved teaching practices, and virtual coaching led to larger crowding-out of home language teaching time. Implementation and survey data suggest technology itself was not a barrier to implementation, but rather that in-person contact enabled more accountability and support.

The original version of this paper was first published in September 2020.