makin', shaken ice cream

Julie had as an activity at the party making ice cream. here's the recipe:
1/2 cup half & half
1 tbs sugar
1/4 tsp vanilla
rock salt
ice
put the first three ingredients in a sandwich-size ziplock and seal. put little bag into a gallon-size bag maybe half-full of ice and half a handful of salt. seal and shake for five minutes or until desired consistency. it was cool and i think fun for the kids. fun to watch too!