Composing ten means to join two numbers to make a set of ten in total. In its more simple explanation, composing ten means to add two numbers together to make ten. This is a basic addition skill that is introduced in late preschool and mastered in kindergarten. Being able to compose ten is an important math skill since our math system is based on sets of ten. Composing ten activities for preschoolers pair well with ten frame activities. If a preschooler has experience in ten-frame math, they are more likely to quickly catch on to composing ten activities.