This Fluency Activity is a part of the Lesson 20, Unit 1, Grade 1. This activity provides continued practice with the commutative property and prepares students for today's objective. It also addresses the core fluency objective for Grade 1 of adding and subtracting within 10. Show students 10 linking cubes in a stick with a color change at the 5, and then remove it from sight. Break off a part and show the part to students. Students make a number bond and two number sentences to match the part shown and the part hidden (commutative property).