Update: Momentum in a Collision

Last winter I shared my Momentum in a Collision activity with you, in which students used rulers to create ramps down which they rolled marbles of varying sizes to observe the transfer of momentum in action. 

Since then, I've had a brainstorm of another, more qualitative way, to complete the activity.

If you know of any young train fans, see if you can get your hands on their wood train tracks, especially the rise-and-fall tracks. 

The parallel grooves on the tracks allow you "run" two marbles at a time and compare the transfer of momentum as they crash into different sized marbles at the end of the hill. 

Train tracks also give you the opportunity to create a nice long runway for the marbles to roll along until they run out of energy.