The supplies needed for this are very inexpensive – a strong rare earth magnet could be had for a buck or too. The aluminum tube could be a bit more, although it might be possible to pick something up for less from a metal recycler. It doesn’t have to be very long. I would say a foot would be enough, although the thicker the walls the better. Copper would be quite a bit more expensive than aluminum, these days especially.
Really, too, there are lots of discrepant events that could serve a similar purpose – palm globe, siphon, drawing water up into a syringe (not as cool) and infinitely many more, many of which would be even more affordable.

Without a doubt. While I do try to get as much into the hands of my students as I can, there are certain aspects of lab experiments that reinforce misconceptions and hide what I really want students to get out of them.

The important part here is to still offer frequent comparisons between simulation and what students are actually observing with their eyes in the world. Otherwise, we run the risk of letting students see a difference between ‘computer world’ and the real world. The computer world is just a model of the real world that gives us a bit more control and access to things that are harder to control in reality.

When students answer the question of ‘what can we measure’ with a request to measure velocity, it’s easy to do that on the computer. It’s a lot harder (and requires some level of hand-waving) to show students how to measure velocity indirectly, particularly when objects have velocities that aren’t constant.

Thanks for sharing

Thanks Mike,

The aluminum tube was one that we had in the store room for a while. I don’t know if it was meant for this activity, but it works great. You could probably pick up a similar one at Home Depot.