Modeling Addition and Subtraction: Lesson 1

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Introduction

Read the Headline Story to the students. They may not know the term area, so space or region may be substituted. Encourage discussion about the meaning of the problem, as well as ideas about the length or width of the rectangle. You might suggest students draw their own rectangles on grid paper.

Headline Story

Lena drew a rectangle on grid paper and shaded it green. Her rectangle covered an area equal to 18 squares on the grid.

Possible student responses

The rectangle could be long and narrow and be 18 squares long and 1 square wide.
The rectangle could include half squares, so it could be $\frac{1}{2}$ square long and 36 squares wide.
If it was 4 $\frac{1}{2}$ squares long and 2 squares wide, it would cover an area equal to 9 of the grid’s squares, and if it was twice as wide as that, it would cover 18 squares.

Headline Story

Modeling Addition and Subtraction, #1

Introduction

Headline Story

Possible student responses