Stand up beside your chair and face the front of the room. Now turn so you are facing the door.

You just made an angle. The turn you did has a name. What kind of turn was it: a small turn, a quarter turn, or a big turn? Was it more or less than turning the whole way back to face the front?

The interactive shows four stills of the orange line opened from a point called the vertex, with the amount of turn on screen. Look at how much it has turned each time, not how long the line is. The four angles are a right angle, an acute angle, an obtuse angle and a straight angle.

Today we'll explore the angle tool together on the board. We will drag the orange line and stop at different turns. Each time we stop, we name the angle: right, acute, obtuse, or straight.

Then, standing in place beside our chairs, we make the same turns with our bodies: a small turn for acute, a quarter turn for right, a big turn for obtuse, a half turn for straight.

Stay in your seat. Together we set the angle tool on the board to different turns and name each one: a right angle, an acute angle, an obtuse angle and a straight angle. After each one, scan the room from your seat and call out a real example you can spot.

What we learned today

• An angle is an amount of turn between two lines that meet at a point called the vertex.
• A right angle is a quarter turn (90°), an acute angle is smaller, an obtuse angle is wider than a right angle, and a straight angle is a half turn (180°).
• The size of an angle does not depend on how long its lines are.