Ice cream in a coffee can!

When I was a Preschool teacher I LOVED this project! It took all day, kept the kids entertained and they took turns willingly!
Ice cream in a coffee can!!!!
You will need a small metal (clean) coffee can, a large (clean) coffee can, ice and rock salt. Mix the following ingredients, trying to get the sugar as smooth as possible.
Ingredients
2 cups milk
1 cup sugar
2 cups whipping cream or half-and-half
2 teaspoons vanilla

Place this mixture in the small can (you will have enough for several) and put the lid on. Put a gallon baggie around the can (in case it leaks) and place it into the large can. Add ice in the area around the small can, add salt. This will need to be replaced periodically. Put the lid on the large can and duct tape closed. Now roll the can back and forth between the children. Checking the product every 1/2 hour. I do not have an exact time as it has been sometime since I have made this. I do remember that it took quite a while. Good luck and good eats!