The math formulas people search game is an activity where students receive a grid with formula prompts in each square. Students get out of their seats and walk around asking for others to fill in one of their squares. I have them sign the square in case of problems with the answer later. Since I have 20 students in my class the directions say they need to find 19 other students to fill in one of the blanks. It is in a word document so you can change the directions to fit your class needs.
I use this activity as a starter in my Algebra 2 class every year. You can also use it in an ACT or SAT prep class.