## Lesson: Three-Digit Addition and Subtraction With Regrouping

Introducing the Concept

Earlier in the year, children learned one- and two-digit addition and subtraction, with and without regrouping. They also worked with place value and money. Review the basic facts and skills they have already learned to prepare them for three-digit addition and subtraction with regrouping. Provide exercises or activities for children to review what they already know. Also provide opportunities for children to share what they know in class discussions.

**Materials:** base-ten blocks (commercial or hand-made), paper or plastic bags, place-value charts, paper, and pencils

**Preparation:** Place 9 hundreds, 20 tens, and 20 ones blocks in a bag for each pair of children. If necessary, create a place-value chart for each pair of children.

**Prerequisite Skills and Concepts:** Children should be familiar with basic addition and subtraction facts and with place-value concepts. Children should also understand how to add and subtract one- and two-digit numbers, with and without regrouping.