For those inquiring minds, ice cream in a bag is very simple to make. You take milk, sugar and flavoring (vanilla, chocolate or strawberry syrup, etc.) and mix them in a small ziplock bag. You can double bag it for extra security if you want. We just poured some in. We didn't measure. However, if you want to measure, I did read somewhere that it is 1/2 cup milk to 1 tablespoon sugar.
Take a big ziplock bag and put ice, salt, and your small bag. Shake it until it thickens. This should take about 5 mins. If you don't put enough salt, it won't freeze. The salt lowers the temp. You will probably want to use a towel or gloves as it gets very cold. Before opening your bag of ice cream, you will want to wipe it off to make sure that no salt gets into the ice cream.
You can also do it in a bowl if you want to. Make the small bag the same way. Then take a big bowl, put ice, salt, and a little water. Then move the small bag around in the ice.
We haven't tried it yet, but I think next time we are going to put m&m's or chocolate chips or some such thing in with the milk also.
Have fun and use your imagination!