There are plenty of exciting educational electronics kits available on the market. The O Watch happens to be an Arduino-based smartwatch to give your kids hands-on programming and 3D design experience. You can customize the watch with 3D printed watch cases and straps.
O Watch is available in two versions. The base watch kit has an Arduino board with a color OLED screen, LiPo battery, 3D printed watch-case, and para-cord kit. The smart version has a sensor board with integrated 3 axis compass, temperature, barometric pressure and humidity sensors. More information is available here.