Grade 4 Math PowerPoint: Angles — Acute, Right, Obtuse and Measuring (17 Slides)

Lesson Sequence

• Open in PowerPoint and start the slide show. Click to reveal each answer after students respond.
• Read the speaker notes (View > Notes) for questions to ask and common mistakes.
• Use with the lesson plan: it lists which slides belong to each lesson.

Teacher Tips

Make the right-angle checker in lesson 1 — students use it all week. Estimation first, measuring second: it stops most protractor errors.

Learning Objectives

• Describe an angle as an amount of turn, and name the arms and the vertex.
• Identify and name acute, right, obtuse and straight angles.
• Estimate the size of an angle using 90° and 180° as benchmarks.
• Measure angles to the nearest degree with a protractor.
• Find a missing angle when angles join to make a right angle (90°) or a straight angle (180°).

Differentiation

Support: Use the paper right-angle checker for every question before naming the angle. Challenge: Introduce reflex angles (more than 180°) and measure them as 360° minus the small angle. English language learners: Pair words with gestures: arms open small (acute), arms in an L (right), arms open wide (obtuse), arms in a line (straight).

What's Included

• 17-slide PowerPoint (PPTX, editable)
• Speaker notes on every slide
• Click-to-reveal answers for questions
• Key vocabulary slide with pictures
• Summary slide to finish the lesson

Teacher Reviews