Build a paper rocket that you can launch via bellows air pressure.
A4 (Explorers) or A3 (Scouts) Stiff paper/ thin card (Set scaling as required when printing), Sissors, Glue, Craft Knife,
Download the files below. You may want to make a Display model first to allow yourself to know and understand any problems they may encounter during the build.
How about creating a league table for who can get theirs the highest.