This is a continuation of the brush bot activity from the previous class. It may be helpful to have some sort of prize, a 3d printed item or a certificate.
Begin by asking if students got their brushbots to work? To move in a way they wanted? What variables were they able to change? Ask if they feel like their minds grew and what did they notice about themselves as they were building and testing their robots.
Setup and run the 750 mm races and the Sumo competition. Here is a link to some rules.
Most importantly have fun, cheer on everyone, and ask questions for them to describe why and how it works.
For the race, I often have the students calculate the cm/s to get the speed.