First step: We pour the milk into the bag and close it.
Second step: We put ice then add salt to cover the bag.
Third step: We use test tube rack to cause movement to the ice which will make the milk freeze.
Fourth step: After the milk starting to freeze, we add toppings to the milk and did the same as step 3 until the milk completely freeze.
Fifth step: We washes our hand and make sure the salt doesn't come into the bag while we are opening.
Sixth step: Enjoy the ice cream
This lab shows us that liquid milk turns into solid by making it cools down. The salt makes the process faster by making the temperature low, so it takes less time than using only ice.
Questions1) why do we add salt to the ice?
It makes the bonds of water change and decreases the freezing point. Therefore, the ice doesn't melt and can cause the milk to freeze.
2) why do we add the cookies and other things, only after the milk has frozen slightly
Because toppings are a heat capacity which can slow the process down.
3) what are two factors that affect the freezing you think?
Movement and temperature
4) why do you need a bit of air in the bag?
A bit of air in the bag allow milk to move and contact with ice.