Growing Rectangles
We have developed a series of activities about growing rectangles for introducing middle-school students to the idea of quadratic functions. These activities serve as a starting point: They address the y = ax^2 + c case, but not the general case.
​
Feel free to use them in your own classroom!
Why Growing Rectangles?
Growing rectangles provide students with a way to understand why quadratic growth has constant second differences. Students can see the first differences as the units of area added to the rectangle as it grows, and the second differences as the rate at which the added units of area is growing. This provides an opportunity to understand how quadratic growth is different and similar to linear growth. One way to do this is to compare rectangles growing in both directions with rectangles growing in only one direction.