Lesson 8

In previous lessons, students used their own methods for subtracting a two-digit number from a two-digit number. In this lesson, students make sense of different subtraction methods that use base-ten drawings to represent decomposing a ten to subtract by place. Students connect base-ten drawings to equations that represent the steps of a subtraction method. Throughout the lesson, students share claims and justify how methods are the same and how they are different with an emphasis on describing how tens are subtracted from tens and ones from ones and deepening their understanding of the properties of operations (MP3, MP7). 

Students should have access to base-ten blocks throughout the lesson and cool-down as they make sense of and try different methods and representations.

What did you say, do, or ask to support students in trying each method for subtracting two-digit numbers from two-digit numbers? What will you do in upcoming lessons to help students make sense of and connect different methods?