Try cases where some variable have the same value than another one.
Think about the case where a = c and b = d.
Then select the option PROBLEM (a+b)(c+d).
You have different options in the menu. The square of (a+b) helps you to understand the square of a binomial.
"Problem (a+b) squaring" generates problems to be solved.
The option "share" allows you to generate 15 problems and theirs solutions that you can send by email.