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3-GM-2-8

Page history last edited by Tashe Harris 6 years, 2 months ago

3.GM.2.8 Find the area of 2-D figures by counting total number of same size unit squares that fill the shape without gaps or overlaps.

In a Nutshell

In third grade, students will learn the importance of “unit squares” and how they can be utilized to find the area of a shape. When measurements are not given, students will use same size squares to fill the shape in order to find the area. This helps students understand what a square unit is, the importance of filling the shape correctly and determine the difference between area and perimeter.

Student Actions	Teacher Actions
Develop accurate and appropriate procedural fluency when finding the area based on the number of squares within the polygon. For example: Instead of just randomly placing unit squares within a shape, students may start by making tightly packed rows or columns. They can count as they go, or count at the end. Communicate mathematically when justifying the area of a 2-D figure.	Pose purposeful questions to help students recall prior knowledge and justify their thinking. Questions may include: What are the most effective ways to find the area of the shape? Are there other methods we can use to find the area? How do the unit squares help us prove the answer to our problem? Implement tasks that encourage students to find the area in multiple formats, such as finding the area of 2-D shapes on graph paper or having students use unit square manipulatives or cutouts to fill the shape. Elicit student thinking when discussing real life scenarios where you would need to find the area.
Key Understandings	Misconceptions
Perimeter is the distance around a shape. Area is the amount of surface within the shape. A procedure needs to be in place to ensure that the squares are being counted accurately. The unit square size is important in order to describe the area accurately.	The area of the rectangle is the same as the perimeter or that they are interchangeable terms. All square units are the same size. For example: 1x1 inch squares are the same size as 1x1 cm squares because they are both represented similarly on graph paper. Units are not important.