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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.

What’s the fairest way to tip at a restaurant? When you go out to eat in the United States, it’s customary to leave a tip as a percent of the total bill. When we do this, though, we don’t compensate servers for how hard they work but rather for how expensive the restaurant is.

Students use percents to calculate tips for different restaurant bills and debate the best ways to compensate waiters and waitresses.

- In the United States, it’s convention to tip as a percent of the total bill at restaurants.
- A tip can be quickly approximated on the fly by reasoning proportionally from 10%. A 20% tip is double 10%; a 15% tip can be thought of as 10% plus half of 10%.
- Tipping as a percent ties server compensation to the cost of food rather than how much work it takes to serve it.

- Reason proportionally to solve real-world problems
- Calculate percent of a whole