Tens Frames are used to teach children complements of 5 and 10. They use these to practice what’s missing from a set to make it complete. The ten frame uses the concept of benchmark numbers (5 and 10) and helps students develop visual images for each number. For example, this device makes it easy to see that 6 is 1 more than 5 and that 6 is 4 less than 10.
There are some great ten frame resources on the web. See these websites for ideas.
Using 10 frames to add and subtract up to 20: http://illuminations.nctm.org/LessonDetail.aspx?ID=L551
Above Reference: http://illuminations.nctm.org/LessonDetail.aspx?ID=L547