This learning center asks students to find the missing addend in an addition problem by using pictures of stairs. The beginning step is identified with a square, and footprints are placed on each numbered stair until the answer is reached. For example, an addition problem might be 2 + ___ = 4. The square is placed on stair number 2. Then there is a footprint on stair 3 and another one on stair 4. Because there are 2 footprints, students can see that the missing addend is 2.

The center includes a set of cards that display each addition problem and its corresponding card number that matches the ones displayed on the student page. Students pull one card and read the addition problem. They use the corresponding picture of a staircase as a clue and write the answer on the student page. When they're done, they put the cards back in the envelope.

Teacher instructions are included for setting up the inside and outside of the folder so students can take the center back to their desks and complete it independently. In addition to supporting independent practice, this activity helps students practice counting on and the concept of "how many more" are needed to reach the total, providing the foundation for more complex math concepts later.