How does the size of the angle change

How does the size of the angle change as the line AC rotates anti-clockwise?

What can you tell me about angles 1 – 5? Which is a right angle? How many right angles make angle 5?

Can you estimate the size of angle 2? Can you estimate the size of angle 4? How did you estimate the sizes?

What can you tell me about angles 5 – 9? How many right angles make angles 7 and 9?

Can you estimate the size of angle 6? Can you estimate the size of angle 8? How did you estimate the sizes?

Estimating Angles Click the icon to practise estimating sizes of angles.

Measuring angles First of all, estimate the size of this angle Cross must lie exactly on vertex A 0 must lie exactly on the line AB C A B Start at 0 and measure anticlockwise

Measuring angles First of all, estimate the size of this angle 0 must be exactly on the line AB C A Cross must lie exactly on vertex A B Start at 0 and follow measure anti -clockwise

Worksheet • Estimate the size of each angle and write it down. • Measure each angle and write down its size. • How close was your estimation to the actual size?

Measuring angles Estimate: Measure: C C A B B A C C Estimate: Measure:

B C C When AB is not horizontal A C A B B A A B C

What if there are no labels?

We know that a half turn = 180° If we make a half turn in stages we could have this: 2 3 1 Measure angles 1, 2 and 3. Check your accuracy – is the total turn 180°?

We know that a full turn = 360° Measure the angles in this pie chart. Check your accuracy – is the total turn 360°?

Here is a 5 – pointed star. Draw a couple of five pointed stars of your own, making sure your lines are nice and straight! Measure the interior angles at the five points and add them together. What do you notice? Do the same for a 7 – pointed star