This Fluency Activity is a part of the Lesson 16, Unit 6, Grade 2. This activity uses dimes and pennies as abstract representations of tens and ones to help students become familiar with coins while simultaneously providing practice with counting forward and back by ten or one. First minute: Place and take away dimes in a 5-group formation as students count along by 10. Second minute: Begin with 2 pennies. Ask how many ones there are. Instruct students to start at 2 and add and subtract 10 as dimes are placed and taken away.