Managing the messiest lab in the world – making ice cream with 8th graders.

January 29, 2012 at 8:36 PM Leave a comment

The end product is today’s reward – make it right, and home made ice cream is so much better than shop bought that it could spoil your palate for ever.

Following recipes is a huge life skill and another dating idea – better even than explaining to the cute stranger why ice floats in their cocktail, you could invite them for dinner and ice cream. But as it’s middle schoolers, let’s stop the images right there.

The smaller the crystals in ice cream, the creamier and better it is. Small crystals form if it freezes very fast. Salt lowers the melting point of water and it’s fascinating to see the thermometer plunge after adding salt to ice, even if you know what will happen, it’s still like magic.

Materials management is key. Learned on my poor first period class again. Got all short and bossy. Tempting to tighten up and do everything for them. Instead, drew the recipe so the directions are as clear as on a brownie mix box and made my expectations clear, concise and simple, including assessing them on lab skills a.k.a. clean up after yourself and don’t throw stuff around!

1. Have the basic, cheap and non-stealable materials in tubs at their tables.:

2. Had the edible ingredients and the ice at central locations as it’s easier to control them. Had a vanilla go missing. WTH? Expensive and spills easily so keep an eye on it.

The teacher’s notes after the activity give extra and more detailed advice for the nuts and bolts of this. Here’s the sheet. 9. WeScreamForIceCreamGMH v2 written by my colleague Greta Heintz. Here is a diagram of the brownie box mix directions.

Before starting, kids knew I’d be evaluating them on following directions and clean up. And if they followed the recipe, their ice cream would be delicious, instead of salty and nasty. Really, really helpful to have another adult in class to help. Thank you Krissy! (And for running the afternoon labs while I went to a workshop. You are a star!)  And thank you Greta for pinch-hitting and doing an ice run – 1 bag per class. It’s a lot!

 Is it worth it for the learning? Good question. I’ll say yes and not because I’m dreaming that they are burning to know why exactly, salt lowers the melting point of water. I think memorable experiences like this act as a hanger for the Calder mobile of their understanding of the concepts around phase changes. Ice, melting, salt and effect of solutes on crystal formation.  Plus it links real life to thermodynamics.

We didn’t try to do heavy-duty teaching with the lab – a fools errand – that was yesterday and in the follow up day. Separate the rigor from the fun:

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Entry filed under: Class Management, Food science, Physics Topics. Tags: , , , , , , .

”I told them a thousand times, those stupid kids.” Distilling The Cost/Benefit of Physical Science/Food Labs

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