Meet the Critter: a 3D printed Arduino robot kit that gets you familiar with coding and robotics. It can also be used to teach your children the basics of 3D design and printing. You can program the robot using C or graphical languages. The Critter uses its two front legs to drag itself. It comes with snap together pieces, so the assembly process is not hard.
The Critter is compatible with Scratch and Blockly. It has an Android app too.