Throughout the 2013 school year, 21 Class 2 teachers and 600 pupils in two rural zones in Kisumu, Kenya, used Tangerine:Class software on 7-inch Android tablet devices as part of a randomized controlled trial (RCT). Tangerine:Class is open-source software optimized for mobile devices that enables teachers to systematically collect, analyze, and use results from continuous assessments of pupils’ early reading or mathematics skills. It is designed for use on smartphones and tablets in low-resource environments without the Internet. Tangerine:Class not only facilitates the administration of continuous assessments but also helps teachers understand results. The software provides guidance to inform instructional decisions about pacing and ability grouping and suggests activities to promote parental engagement. It can be applied for early mathematics and reading instruction, thus maximizing the value of investment in devices, training, and support.