This interactive SMARTboard lesson offers 36 slides for students to practice their addition basic facts from the sums of 5 to 20. Critical thinking skills are required to figure out the missing number. Sometimes it is part of the equation and sometimes it is simply the answer. This lesson has differentiated levels of difficulty by either determining an addend or adding 3 or 4 numbers to determine the answer. All slides are self checking and linked for easy use. Great to use with large group, small group, partner work, or even in an independent center. Can be used over and over. Created with Smart Notebook 11 for grades 1-5 depending on the level of the students. Younger students will find it challenging and may need support. Great for older students to strengthen their basic facts and work on speed. MUST have SMART Notebook software to download and use this lesson.