Idea 9of 15Builds onFlip, then flip again
Turn about a point
Where does a shape end up after a quarter turn or a half turn?
Today you'll discover
- which way clockwise goes
- what a 90° and a 180° turn look like
- what stays still in a turn
Think firstA tall triangle, its tip pointing up
Turn it a quarter turn clockwise, the way a clock's hands go. Where does its tip point?
Decide first, then press Next. Watch the tip, and keep the dot still.
Four small grids in a row. The first holds a tall triangle with its tip up and a dot in its middle, the turn point. One at a time, the others show it turned 90 degrees clockwise (tip right), 180 degrees (tip down) and 90 degrees counter-clockwise (tip left), each with a curved arrow and a faint outline of the start. The last step shows an arrow pointing up.
See the whole ideathe big idea and the key word, in one place
The big idea
A rotation turns a shape about a point; 90° is a quarter turn, 180° is a half turn.
Where the tip ends
Start with the tip pointing up, like the clock's hand at 12.
- Startup
- 90° clockwiseright
- 180°down
- 90° counterleft
Easy to get wrongOnly the turn point stays still. Every other point swings round it, and the turned shape is the same size as the start.
Key words
- rotation
- a turn of a shape about a fixed point that does not move
- clockwise
- the way a clock's hands turn: from 12 toward 3
- counter-clockwise
- the opposite way: from 12 toward 9
Ready to use it?
- Turn a shape 90° clockwise, 90° counter-clockwise or 180°.
- Say which turn changed a shape.