Ball Chain Inquiry – STEM

Yeah, I know. Ball chain inquiry?

Ball chain is that chain that keychains and the like have been made out of for years. I’ll bet some of you have seen this before – there are several videos online and “Mythbusters” included it in an episode.












When I saw those videos I had ideas right away for an inquiry piece that would be fairly cheap and easy to do. I haven’t thought enough about it yet to match it to specific standards … but I’m always on the lookout for easy / quick ways to demo inquiry during professional development trainings I do and I saw potential for this right away.

This 250 foot roll came in a few weeks ago but I haven’t had a chance to try out my ideas yet – today not many folks are in the office, so I jumped at the chance to finally mess around with it and see how it works.

Before saying more let’s take a look – click the video below:

One thought I’ve already had besides, “So what exactly causes that to happen?” (is it somewhat on the same principle as a siphon? – ┬áNot sure – just wondering) is to measure out lengths of the ball chain (10 meters say) and time how long it takes to empty the container. Then ask, “How long do you think it would take for say… 20 meters?” (exactly twice as long? … or does it speed up as it falls?) NOTE – I wouldn’t share that with students, let them decide and then in writing explain their thinking. So they need to time it precisely (do more than one trial at each length – probably 3).

Next keep adding lengths to the chain with the connectors and see if students can become accurate at predicting the exact time. AND – then start including various lengths of chain, like 17.4 meters … can they predict that? What math do they require to figure that out? Or involve fractions instead of decimals – “How long would it take 47 3/4 meters to empty?”

Does height play a role? Does it drop at a different rate from different heights? How would we figure that out?

I see lots of possibilities for this. When I get a chance to try this out with teachers and/or students I’ll let you know what I find out … OR – if you get there before me, let us all know in the comments. Any other ideas how this could be utilized as a learning activity?

BTW – I got that 250 foot roll you see in the photo online for $20 and a bag (50 at least) of the connectors for a couple dollars more. (#10 ball chain – it comes in various sizes – that would be another exploration – does different size chain fall at different speeds?)

Learning is messy!

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