Saturday, 19 January 2013

Archimedes' Principle: Volumes using Water

Every so often I like to look at the videos on the TED web site, and this one stayed with me a long time before I realised what I might be able to do with it...

The basics of the idea remained the same throughout, but I came across some blocks to what I wanted to do. The major one was that I was fixated on getting some 10cm x 10cm x 10cm perspex cubes for measuring (easily fixed with measuring jugs... I couldn't see the forest for the trees).

The main 'objective' of the lesson was to calculate the volume of irregular solids. I then carried this through to density, using the same video and concept, but this blog is about the volume lesson.

I went to the local pound shop on the weekend prior to our lesson, and purchased an assortment of fine goods. In all, I wanted 9 pairs of things to 'dip' and calculate the volume of.

I spent just under £10 and did get a few things I had lying around the house. We finished with a scented candle, a yo-yo, a plastic wrestler, a Noddy figure, a gun-shaped eraser, light bulbs, [forgotten object], a golf ball and a tennis ball (we haven't yet done volume of spheres).

In six groups of five, pupils dunked, measured water displacement and recorded the volume of three of these objects. In their groups they then created a net, and solid, for a prism of the same volume. This gave pupils an opportunity to discuss and consolidate their understanding for the volume of a prism through creating their net.

To finish up, we collected the created solids and compared them against their measured objects. This allows for a discussion regarding the comparison between them (unexpected outcomes, perhaps) and also for a discussion regarding whether our calculated volume would actually be that value for the yo-yo, the light bulb and the tennis ball (of course not, given the empty space).

And finally, we looked at a clip from Parks & Recreation in which a local fast food restaurant have started selling a 'child' size drink. The clip shows a discussion taking place over a table in which one person explains that the 'child' size label refers to the drink being the size of an average 'liquefied 4-year-old'. I explained that this is essentially what we had done - melted our solids down and refrozen them in the shape of our prisms.

The following lesson introduced density and gives a nod to Dan Pearcy's blog post as well as using - the same principle as that final video, with the use of my weight to calculate my volume.

The lesson I have just described didn't all occur within one lesson. I intended to be observed using this lesson, but a GCSE English exam was moved in to my room, meaning that my lesson started 20 minutes late, with my tables rearranged to an exam-friendly layout. We finished up the following day, because of 'school life' taking over, it seems. The above is the way that the lesson will run with year 10 in the coming weeks, though!

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