This is a Smartboard activity that allows students to practice problems dealing with balanced equations. Each page has an equation with a missing addend on one side of the equal sign. The student can write the answer on the blank then touch the question mark to check. The correct answer will be revealed when the question mark is touched for immediate feedback. The preview file has thumbnail shots of many of the pages in the file. This can be used in whole group, small group, or as a math center. I also have a similar file with subtraction in my store.