Kids First - Kids Videos and Nursery Rhymes – Kids First is a free kid education app developed and published by USP Studios.
Circuito.io - Instant code and wiring for your project
YouTube Kids - YouTube for the youngins on iOS and Android
library.io - Learn electronics and easily create circuit boards online
ChuChu TV LITE - ChuChu TV LITE Best Nursery Rhymes Videos For Kids is an interesting app to stream more than 1000 videos.
B4R - Development tool for native Arduino programs.