Seeking a cool, easy robot project

My 5 year-old daughter wants to build a robot. I have begun to teach her basic electrical circuits with LEDs, resistors, speakers, etc. She is doing pretty well and usually shows impressive focus and commitment to learning. I am just learning Arduino code myself in order to facilitate her interest and I am loving it!

I want to give her a little reward for being so dedicated: help her build an easy but exciting first robot for her 6th birthday.

What is the easiest cool robot project you have done or have seen? I would really appreciate tutorials with code, if possible, as I am really a beginner myself.

Thanks!