It comes from the Access Excellence collection and is named The Jelly Bean Problem.
In short, the students are trying to get a handful of candy into a plastic bag following these rules:
- The candy must enter through a solid part of the bag.
- The inside of the bag may not be directly open to the external environment.
- The candies entering the bag must remain clustered together.
- Students may work with their hands in the bag to act as the inside of a cell.
- The candy may be eaten only if it enters the bag "cell" under the specified conditions.
It's fun, candy is always an attention-getter, and it relates directly to cells.