This is a lesson prepared for pupils of 9-13 years old with one earlier lesson in scratch. It was first taught for 20 children in class 5C of the Ugglum School in Partille. These pupils of 11 year old needed 60 minutes to build the base version of this game themselves. In that version, there is no timer to finish the game. Explanations are available in the iBook "Teaching Scratch".
This project is described in the iBook "Teaching Scratch" and can be used for teachers and parents that want to teach children Scratch.