Here is another STEM kit that helps you get your kids familiar with robotics and coding. The LittleBot Plus Robot Kit consists of a fully 3D printed robot. It lets you add sensors and grippers to do more with it. The robot runs autonomously but can be remote controlled. It comes with a free Android app.
You will have to spend about 20 minutes to assemble the robot. The Arduino inside can be programmed via Blockly or C.