I took this photo last summer.
Didn’t know what to do with it. Still don’t. Not enough there for a rich task. A warm-up?
My first question: Suppose Tim Horton’s offers the next size. How much should they charge?
First, students will identify a geometric sequence in the number of Timbit. The common ratio, r, is 2. The next size is an 80 pack.
Students will also need to think about unit prices. And ignore the price-ending-in-nine nonsense. The unit prices are 20¢, 18¢, 16¢. An arithmetic sequence! The common difference, d, is 2¢. The next unit price is 14¢.
Students will solve a problem that involves both — both! — a geometric and an arithmetic sequence. Rare in the textbook, rarer still in the real-world. Okay, this may excite math teachers more than their students.
My follow-up question: Suppose Tim Horton’s continues this pricing. How many Timbits should you get for free?