This cute "Find the Mistakes" activity page (similar to an I Spy worksheet or I Spy Math) is a great way for first grade or second grade students to practice their addition fact fluency within 20. Students search through every number sentence, testing their addition knowledge each time, to find the 6 incorrect facts on the page! A bonus "hidden object" activity is also included on the worksheet for a little extra fun : ) The page is a freebie from my bigger set of 8 worksheets, which you can fin