In previous units, students used methods based on place value to decompose a ten when subtracting within 100. In this lesson, students extend their understanding of decomposing tens to subtract by place within 1,000. In the first activity, students are invited to use whatever approach makes sense to them to subtract one- and two-digit numbers from a three-digit number. In the following activity, they use base-ten blocks to subtract from a three-digit number, and reason about when a ten is decomposed when subtracting by place.