It’s the fourth week of S.T.E.A.M. summer camp and this week the theme is our sense of taste. Well, duh. Of course we are going to make ice cream! Can you believe I have never made ice cream in a bag? It’s such an old school project! Just like last week’s milk carton candles! When I was a kid we had this huge electric ice cream maker that we set out in the back yard and filled it full of ice and rock salt and it was such a treat to be make homemade ice cream. No store bought version compares. It was time to make ice cream with my own kids.
We have a small ice cream machine, but it’s not a very hands on way to explore the science of making ice cream so we decided to make the bag version. After we were done my 6 year old declared,
This is the best science experiment ever!
It certainly is the most delicious.
(Note: I included affiliate links to items we used, below)
What you need:
- Zip top freezer bags in two sizes. I used quart and gallon.
- 1/2 cup half and half
- 1/2 cup ice cream salt (also known as rock salt)
- 1/2 tsp vanilla extract
- 1 TBSP sugar
- Sprinkles. We used Let’s Do Organic Sprinkelz because I eschew chemicals in food. India Tree is another popular brand.
- Favorite toppings.
Fill the larger plastic bag with ice (about half way).
Pour in 1/2 cup salt. (Note: Someone said that this much salt is not healthy. You are NOT eating the salt.)
To the smaller bag, add half and half, sugar, vanilla, and any add-ins. Press out as much air as possible. Close bag.
TIP: Place bag in a bowl when adding ingredients.
Place smaller bag in larger bag. Adjust ice so that it surrounds smaller bag. Press out air. Close bag.
Toss, shake, jiggle, smush, and dance!
TIP: We created a sort of sling out of a dishtowel, placing the cold, cold, cold (brrrr) bag in the towel and gathering the corners at the top. Then we could shake the bag, holding the corners of the dishtowel. Much easier!
After about 5 minutes (or longer, depending on the dedication of your kids) check the ice cream. Shake more if needed until desired consistency is achieved. (This photo is not that great, but you get the idea.)
Eat straight from the bag, or spoon into a bowl and add toppings.
Watch the exciting action!
The science behind making ice cream:
The salt added to the ice lowers the freezing point of ice, causing the ice to melt (we used this same phenomenon in our ice cube on a string experiment). The melting ice absorbs heat, thus making the space around the ice cream ingredients to freeze at a temperature below 32 degrees. Water freezes at 32 degrees, but milk is not just water so it needs a lower temperature.
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