Chapter 3: Angles as Turns

Watch a clock for a few minutes. The minute-hand quietly turns. Open a door , it swings open by some amount, not all the way. Spin yourself once in a circle. Every one of these is a turn. And every turn is an angle.

In this chapter, angles are not just sharp corners on a paper. They are the amount of turn between two arms , like the two hands of a clock. We will learn to spot small turns, big turns, and the special "quarter turn" which we call a right angle.

What's inside

• Turns: full turn, half turn, quarter turn.
• The right angle and how to spot one anywhere.
• Acute (smaller than a right angle) and obtuse (bigger than a right angle) angles.
• Measuring and comparing angles in everyday objects.

How to read this chapter

Read the pages in order , start with turns, then move to right angles, and finally to acute and obtuse angles. Keep a piece of square paper handy to fold; folded corners give you a perfect right angle to compare with.