In "Convergence," Charlie writes "1 + 1 = 2" on the board and gives his students the homework assignment of explaining why he is right and why he is wrong. Most students are familiar with the addition of real numbers. Some might even be familiar with addition of complex numbers.
This activity shows real-world contexts in which we interpret 1 + 1 as a number different from 2. Some examples are explored, but you and your students are encouraged to find more.
Before the Activity
Download the attached PDF and look over the Teacher Page.
During the Activity
Discuss the materials from the Student Page with your class.
After the Activity
Encourage students to explore web sites and questions from the Extensions page.