This is the REX Evolution Robot Kit: it comes with everything you need to make 8 models. It not only introduces your kids to STEM concepts but helps them become better coders with Python. This robot has WiFi and Bluetooth control. It supports block based programming for beginners.
These robots can overcome all kinds of terrains depending on the configuration you go with. You can build an ArmBot, OmniBot, SumoBot, Rover, and a lot more.