While we were getting ready for our ice cream relay, one of the children asked why we needed to add salt to the ice, when making the ice cream. That sounded like a Science Sunday question to me (click the link to visit this week's Science Sunday link-up at Adventures in Mommydom).
You can find the ice, and salt answer in a pretty nice YouTube clip from Science on the Brain, but there's nothing quite like a hands on experiment, for getting to the bottom of a science mystery. And, since solving this particular mystery involved making more ice cream, the children were very gung ho to give it a try themselves.
We started out with a normal, ice cream in a baggie, set up. We filled two pint sized bags, each with:
- 1/2 cup of milk (you can use heavy cream, or even half and half, for a creamier ice cream, but even 1% milk will get you something yummy)
- 1/4 teaspoon vanilla
- and 1 tablespoon sugar.
We closed the bags up, and dropped them into gallon sized freezer bags, filled with ice.
We sealed up one bag, and added six tablespoons of rock salt to the other, before sealing it...
...and marking the bag, so we could tell the two apart.
Then, we set a timer for ten minutes, and took the bags outside for a good shake.
You could be really scientific, and take the temperature of the ice in the two bags, but we found the bag with the salt was significantly colder to the touch, than the bag with just ice (thanks to the salt, which reduces the freezing temperature of water).
And, after ten minutes, the milk mixture in the bag with salt, was completely frozen, while the other bag still contained milk...
...really good, and cold, vanilla milk, but still milk.
A, is very fond of vanilla milk, so it didn't go to waste.
Neither did the ice without salt. After the younger girls finished off the ice cream...
...they used the unsalted ice cubes to "color" in one of their paint-with-water books, knocking another must-do off our summer list.
So, we had science, a snack, a craft, and beat the heat at the same time. Not too bad for a sunny, Sunday afternoon.
It's great to be a homeschooler.