- Connect to student understanding of sequences and series (which we had studied the previous weeks), percent, and functions (mine haven't studied exponential growth yet).
- Get students discussing concepts such as interest rates, loans and repayments
- All my students were very actively engaged with thinking and arguing about this activity
- Somewhat self-checking, especially once I told the kiddos that the two columns should be of equal length
What to do:
- Cut out each rectangle and give small groups of students a set of all the rectangles.
- Tell them to sort them into two categories. Or don't tell them the number of categories.
- Eventually hint that the categories should have equal number of rectangles.
- When groups are almost done, walk around and check on their categories, giving hints and pointing out conflicts without giving the solution to the conflict.
When groups are done, I lead a whole class discussion in which the main ideas of simple and compound interest were introduced and defined, and students got a few minutes to derive the general formulas for these types of interests.
I ended the lesson by asking how much Jesus would have had in the bank today, if his parents had invested 1kr at 1% annual interest when he was born. This helped students get the idea that given enough time, compound interest far outgrows simple interest.