Thursday, August 9, 2007
Ice Cream Day!
It has been too hot. By "too hot" I mean that at 7 am it's 84 degrees but feels like 90 because of the swamp like humidity. Days of triple digits... what to do? Haul out the little inflatable water park? Great, but you can only spend so much time there. How about declaring it to be Ice Cream Day?
Worked for us! We downloaded bunches of ice cream themed work sheets from Enchanted Learning: Venn diagrams, word searches, fractions, etc. We made fabulous construction paper ice cream cones. Zorg made a dish of paper ice cream that stretched nearly from floor to ceiling complete with sprinkles, syrups and a cherry on top. And of course we made actual ice cream: chocolate chocolate chip and strawberry blackberry. Plenty of science there!
One thing to look at: How does the ice cream get colder than the melting ice? Every time matter changes phases it either takes on or gives off energy. Another way of looking at that is to say that it takes energy for matter to change phase. You can lower the temperature of water to 32 degrees without freezing it (ice water is 32 degrees). You need to remove more heat (energy) to change the 32 degree water into ice (although the ice can still be 32 degrees, the heat/energy removed is in the phase change not the temperature). The reverse is also true: when you melt the ice with salt (around the ice cream freezer) the phase change absorbs energy and the temperature of the salty water drops (it won't refreeze because of the presence of the salt). Where does it get the energy from? From the heat in the ice cream makings. The heat is absorbed by the salt/ice reaction, the temperature drops and your ice cream freezes!
If your kids are too young to get that, you can do a fun experiment seeing whether ice cream melts faster in a plastic or metal spoon. Good chance to talk about specific heat and why some things feel colder than others at room temperature.
Ahh, sweet, slurpable science!!!!!