When dealing with the conservation of momentum we rarely get past two particle problems, so the statement that for a system of isolated bodies the total momentum is constant, is acceptable for two bodies, but seems a bit of a leap to extend this to a large number of bodies. I know Algodoo is a simulation so of course obeys the laws of physics but it's useful to see what collisions look like when the rules are followed. Here I have made a collision between one ball and two others, the "show momentum" option has been ticked for all 3 balls so the momentum vectors are displayed. I then copy the before and after images into a Notebook file, this is the SMARTboard software and use the drawing tool to make copies of the momentum vectors to show that momentum is conserved. I am starting to show more and more demos, simulated and real, to my students in the hope that they will form the seeds for IA investigation ideas.

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