Place Jell-o in two plastic zip-loc bags and if you have one, a square container. Lemon flavor is light colored to make it easier to see inside. The square container is a plant cell. The other is an animal cell.
Then organelles can be placed in the “cells.” Mandarin orange slices could be mitochondria. Grapes, chloroplasts, could go in the square container. The nucleus, maybe a plum, should be in each cell.