LEARN · PRACTISE · DISCOVER

Explore Lines and Angles

Read at your own pace. Try the practice, then continue your course.

Recognize line segments, parallel and perpendicular lines, and measure angles by the size of their opening.

This lesson is for members

Join to unlock this lesson and the full course library, or log in if you are already a member.

THE CURIOSI · EXPLORE & TRY

Explore the model, then test your understanding. Select each numbered stop to discover its role.

Learning diagram: use the labelled values. Screen size changes, so these pictures are not calibrated measuring tools.

1Acute 45°

An acute angle is greater than 0° and less than 90°.

2Right 90°

A right angle measures exactly 90°.

3Obtuse 120°

An obtuse angle is greater than 90° and less than 180°.

4Angle size

Extending the arms does not change the angle between them. Rotation also leaves its size unchanged.

Use matching units and the stated properties. Explain whether your answer measures length, area or volume.

Choose one answer for each question, then check. Practice results stay on this page and do not change course completion.

1. An angle of 120° is… Right Obtuse Acute

2. Perpendicular lines meet at… 90° 45° 180° only

3. Making both arms longer changes the angle size… Always doubles it Always halves it Not at all

Read the answer explanations

For hands-on practice, use a real ruler, square paper or blocks. Keep units visible and explain your method.