Illustrative Mathematics
Equal Area Triangles on the Same Base II
A deceptively simple question setup leads to a number of attack methods and a surprisingly sophisticated solution set in this open-ended problem. Young geometers of different strengths can go about defining the solutions graphically,...
Illustrative Mathematics
Overlapping Rectangle
Challenge young mathematicians' ability to compose and decompose shapes with this fun geometry puzzle. The goal is simple, locate all of the rectangles shown in a picture of three overlapping rectangles. Perform this activity as a whole...
Illustrative Mathematics
Counting Squares
Challenge young mathematicians' understanding of squares with this geometry puzzle. The task is simple, identify as many squares as possible in a 3x3 array. Allow learners to work independently or in pairs as they search for squares,...
Illustrative Mathematics
Ants Versus Humans
You would think that humans make up more mass than ants do on this planet, but think again, and this time by performing calculations. Middle schoolers use scientific notation to compute and compare the estimated total mass of all humans...
Curated OER
Rating Systems
Your favorite sports team is ranked #1. How do the powers that be determine this rating? Learn how ratings are mathematically computed using probability concepts, from the Elo Rating System for chess to the Rating Percentage Index for...