# Lesson Plan: Part–Whole Bar Models: Numbers up to 20 Mathematics • 2nd Grade

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to use part–whole bar models to solve one-step addition and subtraction problems.

#### Objectives

Students will be able to

• write an equation to represent a part–whole bar model,
• find a missing number in an equation represented by a part–whole bar model,
• recognize whether addition or subtraction is needed to solve a problem represented by a part–whole bar model,
• draw and complete a part–whole bar model for a given word problem,
• use addition or subtraction and part–whole bar models to solve a word problem.

#### Prerequisites

Students should already be familiar with

• addition and subtraction within 20,
• addition strategies, including making 10, using doubles, and using near doubles,
• subtraction strategies, including counting on, counting back, and using a number line.

#### Exclusions

Students will not cover

• numbers greater than 20,
• comparative bar models.