Here is a LEGO kit that lets your kids build fun robots with Bluetooth. The LEGO Boost Creative Toolbox comes with over 840 LEGO pieces, including sensors, motor and Bluetooth enabled hub for you to get started. Its color & distance sensors detect distance, motion, and color.
You get to build 5 models with this kit (Guitar 4000, Vernie the Robot, MTR 4, Auto Builder, Frankie The Cat). Just bring your smart device with the LEGO boost app to get started. This STEM kit is available for under $160 at this time.[where to get it]