Prepare the jelly according to the instructions on the package. Fill as many small glasses as one would expect children with the jelly the evening before. You have to estimate the amount depending on the size of the glasses.
Pour approx. 1/4 of the liquid jelly into a mixing bowl and let it set too. Then in the morning whip the jelly in the bowl with the electric whisk until frothy. Put this foam on the glasses with a teaspoon.