This activity is great for a warm-up the day after teaching combining like terms. You give each student number tiles 0 - 9 (they can just be made on paper, nothing fancy), and a copy of the activity turned over (I like to use dark colored paper so they can't see through it. When you say go they turn it over and fill in the blanks with the number tiles. There are five problems, two blanks per problem. One blank is in the problem and one is in the answer, so they have to be able to go back and forth, a great higher order thinking skill!
This is a quick activity. I will give a prize to the first five that finish, which makes them want to work quickly!