First, show students how to factor and expand the difference of two squares using algebra tiles, and have them practice doing so. In this lesson, students will see zero pairs in the context of algebra tiles. They should already know about zero pairs in terms of counters from their previous work with adding integers. Then teach them the general formula for the difference of two squares and how the formula is derived. Here's a good video for teaching how to use the formula. You should also teach them why the sum of squares is not factorable. Finally, have them practice using the formula to factor and expand various expressions. After doing all this, give them this challenge. The aforementioned challenge is quite difficult. Don't be surprised if most students fail.