Year level: 4

Strand: Measurement

Lesson length: 45 mins

In this first of two lessons, students explore ways to compare angles and recognise the names of different types of angles, including right, acute, obtuse, straight, reflex and revolution.

In a follow-up lesson, Angles: chalk design, students create their own chalk designs in the style of a stained-glass window that includes different types of angles.

### Achievement standard

By the end of Year 4, students compare angles relative to a right angle using angle names.

### Content descriptions

Students estimate and compare angles using angle names including acute angle, obtuse angle, straight angle, reflex angle and revolution, and recognise their relationship to a right angle. AC9M4M04

### General capabilities

Numeracy

• Understanding geometric properties Level 4

Critical and Creative Thinking | Inquiring Level 3

• Identify, process and evaluate information
• Use observation and informal conversations to access students’ proficiency in identifying, describing and representing right angles, acute angles, obtuse angles, straight angles, reflex angles and revolutions.

Some students may:

• have relatively limited experience with angles, how angles are measured, the names of different angles and their relationship to right angles
• not yet be familiar with the idea that angles are measures of turn and that we can estimate the size of angles using a right angle as a starting point or benchmark
• be unfamiliar with the names of the different angles, so it will be important to create a visual chart to help them to become more familiar with the names of the different angles and how the size of each angle can be compared to a right angle.

Prior to this lesson, it is assumed that students have knowledge of:

• angles as measures of turn
• how to compare angles to right angles (greater than or less than) in everyday situations
• how to identify patterns of geometric shapes in the environment.

## What you need:

• Lesson plan (Word)

• Teacher’s slides (PowerPoint)

• Scissors, split pin and card to create an angle checker