Fold the elastic band flat.
Tape one end of the flattened elastic band to the end of the skewer, making the tape really tight around the skewer, so that the elastic band is held on firmly.
Slide the straw onto the other end of the skewer.
Lay the free end of the flattened elastic band over the straw and tape tightly to secure the elastic band to the straw, but without taping the straw to the skewer.
Hold the jumper upright on the desk and pull the straw down to the desk so that the elastic band is stretched.
Let go of the device in one go, by separating your fingers wide quickly.
It will jump in the air by about half a metre.
Students need to be instructed on using it safely - do not jump it towards anyone.
Ask students to think about the chain of energy transfer that happens as the toy is used.
Chemical energy - from our hands as they pull down on the toy
Motion energy - as the toy is pulled down
Elastic energy - as the elastic band is stretched
Motion energy - as the toy is released and the elastic band pushes it upwards (also sound energy as the straw hits the top of the stick)
Gravitational energy - as the toy is up in the air
Motion energy - as the toy falls back down
This activity is from the Children's Museum of Houston: http://www.cmhouston.org/stretch-your-potential