This SMARTboard activity is a great way to reinforce and practice basic math facts up to 20. Two problems with a missing number are given on each slide. The correct answer will solve both equations. Both addition and subtractions included. All slides are self checking so it is easily used in a teacher directed mini lesson, small group, or an independent center. Do you have 5 - 10 minutes before lunch, recess, or dismissal? Why not practice your math facts. Created with Smart Notebook 11.