You think?

So we just started learning about exponents today. For the journal I posed the following scenario:

Suppose your allowance doubles every week. This week you receive $2.56.

1. How much will your allowance be three weeks from now?

2. How much was your allowance three weeks ago?

3. From a parent's point of view, is doubling your allowance each week a good plan? Explain.

At least half of all of my students thought it was a good plan. I should have had the homework be explaining the situation to their own parents and asking them if they thought it was a good idea. I imagine we'd get very different answers.