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LESSON PLAN
Angle Measurement and Classification
A
Apothem Team
Grade 6 · Geometry
LESSON AT A GLANCE
Warm-up
5 min
Explore
15 min
Formalize
10 min
Practice
12 min
Exit ticket
3 min
Warm-up
Show a 90° angle (right angle). Ask students to point to right angles in the room.
Explore
Students sort angle cards by type (acute, right, obtuse, straight, reflex). Then, they use protractors to measure. Emphasize: estimate first, then measure.
Formalize
Record the five angle types with degree ranges:
Acute: 0–90° | Right: 90° | Obtuse: 90–180° | Straight: 180° | Reflex: 180–360°
Teach the protractor method step by step. Practice with a few clear examples.
Practice
Students classify and measure 6–8 angles using protractors. Exit ticket: classify and measure one angle.
Exit ticket
Students classify and measure 6–8 angles using protractors. Exit ticket: classify and measure one angle.
TIP Many students struggle with protractor use. Model the process multiple times and have them practice with very clear angles first.
WORKED EXAMPLES
Measure this angle with a protractor.
Align center at vertex, one ray at 0°, read the other ray: 65° (acute).
Classify a 145° angle.
Obtuse (between 90° and 180°).
MATERIALS
•Protractors
•Angle cards
•Rulers
•Paper strips (for making angles)
WATCH FOR
!Using the wrong scale on the protractor (inner vs. outer).
!Not aligning the center of the protractor at the vertex.
!Confusing reflex angles with their non-reflex counterparts (e.g., 70° vs 290°).