I have received this lesson fifth hand and seen multiple variations with colorful additions, but it boils down to this:
Here’s a stack of 6 plastic cups. The company you work for is needs to know what size of box to use to ship the cups in stacks of 50. How tall will the box be?
I have done it this way and it made a straightforward lesson with an intuitive linear relationship.
Last summer when doing this lesson with 9th graders, it came out (by accident) this way:
Here’s a stack of 6 plastic cups. Design a box to hold 50 of these cups.
A wildly different lesson ensued. Some students assumed one stack of 50, some students used two stacks of 25, some students made 10 stacks of 5, and some came up with even more exotic ideas including non-rectangular boxes and uneven stacks.