Types of Angles Worksheet

Lesson Overview

About this worksheet

Classifying angles by type is the foundation skill that supports later work in triangles, polygons, and protractor measurement. This worksheet teaches the classification through three lenses: visual identification (Section A), recall of the degree boundaries (Section B), and applied judgment with given measures (Section C). A reference box on page 1 defines all four angle types — acute, right, obtuse, and straight — with the degree count for each.

Section A presents six angles drawn as two rays from a labeled vertex. The right angle (item 2) is marked with the standard right-angle square; the other five angles carry a small arc indicating the angle being measured. Section A covers acute, right, and obtuse angles directly; the straight angle (180°) is covered through Section B text items because a straight angle visually reads as a single line and is easier to recognize by definition than by figure.

Section B drills the degree boundary facts (acute < 90, right = 90, straight = 180, obtuse 90–180) and asks students to classify three specific angle measures. Section C closes with three short word problems that ask students to classify a given measure and, in item 17, recall the right-angle notation. The answer key on page 3 includes a brief justification in parentheses (e.g., "acute (less than 90)") so the AK doubles as a teaching reference for students who need a hint.

How to Use This Lesson

Read the reference box together and have students point to a real-world example of each angle type in the classroom (right angle = corner of a book, etc.).

Complete Section A items 1 and 2 as a class to model the difference between an acute angle and a right angle on the same axis.

Have students complete Section A items 3–6 independently or in pairs.

Discuss Section B as a class — the boundary facts (less than 90, exactly 90, between 90 and 180) are best memorized through oral repetition.

Use Section C as a quick exit ticket; review the answer key on page 3 with the parenthetical hints so students see the reasoning behind each classification.

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