The overall goal of this study is to enhance school readiness assessment in Kenya by developing an easy-to-use tablet-based android app that can support teachers and learners during the assessment of Pre-academic skills, Mastery Motivation (MM) and Executive Functions (EF) in the Kenyan context. We operationalised MM and EF as components of Approaches to Learning (ATL): one of the poorly assessed domains of school readiness. This research was based on the theory of ATL and followed a non-experimental longitudinal research design. One study was a Scoping Review that identified the gap in the literature in the assessment of School Readiness domains using game-like apps. This study formed the basis for developing Finding Out Children’s Unique Strengths (FOCUS) app for Kenya following Education Design Research Approach. Two studies tested and evaluated the psychometric properties of the FOCUS app in the Kenyan context. Another two empirical studies focused on adapting the Preschool Dimension of Mastery Questionnaire 18 (DMQ 18) and the Childhood Executive Functioning (CHEXI) to complement the assessment of MM and EF, respectively. In addition, one study addressed the role played by MM and EF on school academic performance. A total of 40 teachers, 497 preschool and 535 grade 1 children were involved in this study. Both parametric and non-parametric statistical analyses were used to analyse the generated data. The FOCUS app, CHEXI and DMQ 18 fit well with the data and exhibited strong psychometric properties, thus being suitable for the Kenyan context. Furthermore, both MM and EF were directly and indirectly, involved in grade one children’s academic performance. FOCUS app tasks, pre-academic skills, and number and letter search tasks at preprimary II strongly predicted preschool and grade one academic performance. MM assessed using the FOCUS app as a better predictor of academic performance than the DMQ 18. Interventions to improve MM and EF promise to enhance School Readiness in the Kenyan context. The FOCUS app can greatly complement Kenya School Readiness Test to give teachers and parents a broader spectrum to make correct decisions concerning the child.