2022 3-GM-1-3

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3.GM.1.3

3.GM.1.3 Classify angles within a polygon as acute, right, obtuse, and straight.

In a Nutshell

This objective asks students to identify the angles within a shape based on the vertices and then classify them as acute, right, obtuse, or straight. In second grade, students learn what a right angle is and identify if an angle is bigger or smaller than a right angle. In third grade, students will learn the names of specific angles and identify them within a 2-D shape. Understanding angles help students describe a shape and understand what rays are in 4th grade.

Student Actions	Teacher Actions
Demonstrate understanding of how to classify the different types of angles within polygons. Communicate mathematically as to why angles are obtuse, acute, or right. Demonstrate a deep and flexible understanding when describing two-dimensional shapes and the type(s) of angles it contains.	Pose purposeful questions to help students recall prior knowledge and justify their thinking. Questions may include: How can this be modeled? Can you justify your thinking? Facilitate mathematical discourse when students explore shapes and their angles. Implement tasks that create opportunities for students to describe shapes and their angles.
Key Understandings	Misconceptions
The length of the sides does not affect the size of the angles. Shapes can have more than one type of angle	Obtuse and acute angles are the same thing. Angle size is dependent upon the size of the side lengths.
Knowledge Connections
Prior Knowledge	Leads to
Recognize right angles and classify angles as smaller or larger than right angles (2.GM.1.5)	Measure angles in geometric figures and real-world objects (4.GM.2.1) Measure and compare angles according to size (5.GM.3.1)
Sample Assessment Items
The Oklahoma State Department of Education is releasing sample assessment items to illustrate how state assessments might be designed to measure specific learning standards/objectives. These examples are intended to provide teachers and students with a clearer understanding of how the state assesses Oklahoma's academic standards and their objectives. It is important to note that these sample items are not intended to be used for diagnostic or predictive purposes. Ways to incorporate the items. 3.GM.1.3 Acute, Obtuse, Right