Idea 3of 24Builds onLay one angle on another
Count wedges to measure an angle
How can a small paper wedge measure an angle?
Today you'll discover
- how to measure an angle by counting
- how much bigger one angle is
- why a smaller wedge gives a bigger count
Think firstAngles P and Q, and one paper wedge
How can this one wedge tell you how big each angle is?
Decide first, then press Next. Count the numbered slices in each angle.
Angle P and a wider angle Q, with one small paper wedge drawn above them. Copies of the wedge then fill each angle edge to edge, numbered: 3 in P and 5 in Q. A line across the top says Q is 2 wedges bigger. Then a wedge half as wide fills P 6 times. The last step shows a narrow P and a wide Q to be filled with the first wedge.
See the whole ideathe big idea and the key word, in one place
The big idea
To measure an angle, count how many copies of one small unit fill it.
Compare themLaying one angle on another says which is bigger. Counting units says how much bigger: Q is 5 wedges, P is 3, so Q is 2 wedges more.
Easy to get wrongFill the angle edge to edge. Gaps between wedges, or wedges piled on top of each other, make the count wrong.
Key word
- unit of angle
- a small angle used over and over, with no gaps, to measure a bigger one
Ready to use it?
- Measure an angle by counting wedges.
- Say how many wedges bigger one angle is.