EngageNY 60 min(s)

In this lesson, students solve using Rekenrek bracelets and number bonds to show how "partners of 9" lead to related subtraction number sentences. For example, they notice that 9 - 8 = 1 and 9 - 1 = 8 are shown in similar ways with their Rekenrek bracelets (both starting with 9, and involving a group of 1 and a group of 8), and that knowing one subtraction sentence allows them to quickly know the other.