Coding as another language: Research-based curriculum for early childhood computer science

•Evidence-based early childhood computer science curriculum utilizing the free ScratchJr programming, Coding as Another Language (CAL).•Results from cluster randomized controlled trial show CAL’s feasibility to implement, and effectiveness for improving coding skills.•Despite the time taken away from the math and literacy blocks to teach CAL, standardized test for literacy improved and math remained the same.•During the cluster randomized controlled trial, both the control and the intervention groups improved equally on computational thinking.