Here are some pairs of equations. While one partner listens, the other partner should: Choose a pair of equations from column A. Explain why, if x is a number that makes the first equation true, then it also makes the second equation true.

Choose a pair of equations from column B. Explain why the second equation is no longer true for a value of x that makes the first equation true.

Then, switch roles until you run out of time or you run out of pairs of equations.