In the fall of 2024, Citizen Math released updated versions of every lesson in our library, plus a few new ones! We know you may have already prepped an earlier version or planned a repeat of last year, so we're continuing to make these earlier versions available through Thursday December 5, 2024.

You can find the new lessons through the regular search, and we hope you love them as much as we do. You can read more about these updates in Our Community.

How much would it cost to get all the toys in a Happy Meal? The McDonald’s Happy Meal is a cultural phenomenon. Parents like it because it’s a quick and easy meal, and kids like it because it comes with a toy (typically part of a larger set).

Students use trials, probabilities, and expected value to determine how many meals it takes to get a complete set of Happy Meal toys and debate whether McDonald’s should allow customers to pay a fee to choose their own figurine.

- When trying to collect a full set of Happy Meal toys, the chance of getting a new toy decreases as you collect more toys.
- The expected cost of acquiring a new toy, then, also increases.

- Create frequency distribution from experimental data and interpret the results
- Use theoretical and experimental probability to reason about real-world decisions
- Calculate expected value and use it to evaluate decisions in a real-world context