Geometry — Study of Angles

Angles come from lines meeting. The right angle (90°) is the foundational reference; others are comparisons. Children handle the wooden angle frame and see acute as 'less than right,' obtuse as 'more than right but less than straight.' Measurement discrepancies — child's estimate vs. protractor reading — are the control.

• Framework: Montessori
• Unit: Mathematics
• Learning area: Geometry
• Level: Ages 6-7

Objectives

• Name the types of angles: right, acute, obtuse, straight, reflex, full
• Measure angles with a protractor
• Match angles to real-world examples
• Prepare for triangle classification

Materials

• Angle nomenclature cards
• Wooden angle-measuring frame (movable arm)
• Protractor
• Paper and pencil

Instructions

1. Introduce the wooden angle frame. 2. Set it to a right angle (90°). 3. Name this 'right angle.' 4. Narrow the angle: 'acute — less than a right angle.' 5. Widen past 90°: 'obtuse.' 6. Continue to 180°: 'straight angle.' 7. Beyond 180°: 'reflex.' 8. At 360°: 'full angle.' 9. Measure real angles (corner of a table, open book, clock hands) with a protractor.

Educator tip

A clock is a living angle-machine. Set times and measure the angle between hour and minute hands.

Assessment

Note angle-type naming, protractor use, and estimation accuracy before measuring.

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• Fractions to Decimal Fractions
• Pythagoras Plates — Sensorial Proof of the Theorem
• Algebraic Peg Board — Equations and Signed Numbers
• Word Problems with Materials
• Short Chains — Squaring Visualized
• Ratio and Proportion
• Volume — Measuring Three Dimensions
• Factor Trees and Prime Factorization