My students love Write (or in the case Add) the Room activities. The goal of this one is to provide practice mental addition of tens and hundreds to 3-digit numbers. It's a low-prep activity. Print one copy of the equations, and enough recording sheets for each student. Cut the equations apart and tape them around the room, and you're ready to go!
Students are asked to determine the missing addend in equations with sums up to 1,000. They are required to note which digit changes, and by how many tens or hundreds. It's sure to get them thinking as they practice important Base-10 concepts.
Color and black and white versions are included, along with a recording sheet for answers.