In previous lessons, students learned that decomposing a ten is sometimes necessary when subtracting. Students used connecting cubes and base-ten blocks to represent their methods when subtracting a one-digit number from a two-digit number. Students build on these skills in this lesson.

In the first activity, students use methods that make sense to them to subtract and compare their methods with a partner. In that Activity Synthesis, students make connections across different methods and representations and consider which tools and representations work best for them. In the second activity, students use base-ten blocks to represent expressions and decompose a ten when subtracting by place.

Students should have access to connecting cubes and base-ten blocks throughout the lesson and the Cool-down.