## Description

# What our Add and Subtract to 20 Using Models lesson plan includes

Lesson Objectives and Overview: Add and Subtract to 20 Using Models teaches students how to add and subtract to 20. At the end of the lesson, students will be able to use addition and subtraction within 20 to solve word problems by using objects, drawings, and equations with a symbol for the unknown number to represent the problem. This lesson is for students in 1st grade.

### Classroom Procedure

Every lesson plan provides you with a classroom procedure page that outlines a step-by-step guide to follow. You do not have to follow the guide exactly. The guide helps you organize the lesson and details when to hand out worksheets. It also lists information in the blue box that you might find useful. You will find the lesson objectives, state standards, and number of class sessions the lesson should take to complete in this area. In addition, it describes the supplies you will need as well as what and how you need to prepare beforehand. The supplies you will need for this lesson are pencils, pens, and highlighters.

#### Options for Lesson

Included with this lesson is an “Options for Lesson” section that lists a number of suggestions for activities to add to the lesson or substitutions for the ones already in the lesson. One optional addition to this lesson is to create centers for students to model problems. You can also get your students up and moving by bringing in objects for students to model various scenarios with, such as having apples or mini-dogs for them to use during the lesson activity. For another additional activity, you could line students up and play human addition and subtraction. Finally, try calling out a problem and having your students line up showing the answer (for example: 3 girls + 2 boys = five people).

### Teacher Notes

The teacher notes page includes a paragraph with additional guidelines and things to think about as you begin to plan your lesson. This page also includes lines that you can use to add your own notes as you’re preparing for this lesson.

## ADD AND SUBTRACT TO 20 USING MODELS LESSON PLAN CONTENT PAGES

### Add and Subtract to 20 Using Models

The Add and Subtract to 20 Using Models lesson plan includes three pages of content. The lesson begins by explaining that you can solve addition and subtraction word problems by drawing pictures. Using objects can help show you what is happening in a problem. The lesson then includes three example problems with pictures to illustrate this.

In the first example, someone has 8 cats. 3 of the cats are yellow and the rest are brown. How do you figure out how many of the cats are brown using pictures? First, draw 8 cats. Next, make 3 of them yellow and color the rest brown. Finally, count the number of brown cats. There are 5 brown cats. We can also show this using subtraction: 8 (total cats) – 3 (yellow cats) = 5 brown cats.

In the second example, there are 7 apples total, some of which are green and some of which are red. What are the possibilities for how many apples could be red or green? First, draw 7 apples. Next, color in each possibility and write the addition sentence next to the model. For the first model, all the apples are green. The addition sentence is 0 (red apples) + 7 (green apples) = 7. For the second, color in 1 apple red and the rest green. The addition sentence is 1 (red apple) + 6 (green apples) = 7. Continue until you’ve drawn all of the possibilities and written addition sentences for all of them.

In the third example, Helen has 12 library books and Maria has 9. How many fewer books did Maria check out than Helen? To solve this problem using models, first draw 12 books for Helen and 9 for Maria. Next, cross out the books that overlap. Count the remaining books in Helen’s row to discover that Maria checked out 3 fewer books than Helen.

## ADD AND SUBTRACT TO 20 USING MODELS LESSON PLAN WORKSHEETS

The Add and Subtract to 20 Using Models lesson plan includes three worksheets: an activity worksheet, a practice worksheet, and a homework assignment. You can refer to the guide on the classroom procedure page to determine when to hand out each worksheet.

### CARDS ACTIVITY WORKSHEET

The activity worksheet asks students to first cut out both number cards and cards with numerical symbols on them (+, -, and =). They will then read word problems and use the cards to write different addition and subtraction sentences to solve each problem. Each problem has multiple answers.

### WORD PROBLEMS PRACTICE WORKSHEET

For the practice worksheet, students will solve four word problems. They must show their thinking using pictures.

### ADD AND SUBTRACT TO 20 USING MODELS HOMEWORK ASSIGNMENT

The homework assignment asks students to solve two problems using models.

### Worksheet Answer Keys

This lesson plan includes answer keys for the practice worksheet and the homework assignment. If you choose to administer the lesson pages to your students via PDF, you will need to save a new file that omits these pages. Otherwise, you can simply print out the applicable pages and keep these as reference for yourself when grading assignments.