Idea 4of 24Builds onCount wedges to measure an angle
A degree is a tiny turn
Why does everyone measure angles in degrees?
Today you'll discover
- how many degrees make a straight line
- how a protractor counts degrees
- how many degrees make a square corner
Think firstA straight line is half a turn
Everyone uses the same tiny wedge, called a degree. How many degrees make a straight line?
Decide first, then press Next. Count the small ticks along the curved edge.
A straight line with a dot at its middle. A half-circle protractor is then laid on it, marked with a small tick for every degree and numbered every 10 on two rings, from 0 to 180. Then an angle whose second arm crosses the scale at 70, with a curved arrow counting up from 0 to 70. The last step shows a square corner.
See the whole ideathe big idea and the key word, in one place
The big idea
A degree is a tiny turn; 180 degrees make a straight line.
Why a protractorCounting 70 tiny wedges by hand is slow. A protractor lines up all 180 degrees with no gaps and numbers them in tens.
Write it short70 degrees is written 70°. The small circle means degrees.
Key words
- degree
- the standard unit for angles: a very small turn; 180 of them make a straight line
- protractor
- a half circle marked in degrees, used to measure and draw angles
Ready to use it?
- Read the size of an angle in degrees.
- Say how many degrees make a straight line and a square corner.