Idea 11of 15Builds onTurn it, corner by corner
Turn about a corner
What happens when the turn point is a corner of the shape?
Today you'll discover
- why the shape moves as well as turns
- where it lands after 90° and 180°
- how to keep the corner fixed
Think firstAn L whose corner is the turn point
The L turns 90° clockwise about the corner dot. Where does it end up?
Decide first, then press Next. Watch the dot: it never moves.
Four small grids. The first holds an L shape whose corner sits on the turn point, the L reaching up and to the right. The others show it turned 90 degrees clockwise (now reaching down and to the right), 180 degrees (down and to the left) and 90 degrees counter-clockwise (up and to the left), the corner always on the dot.
See the whole ideathe big idea and the key word, in one place
The big idea
Turning about a corner swings the whole shape round that corner into a new place.
Compare themTurning about its middle, a shape stays in its spot. Turning about a corner, it swings round into a different spot.
Easy to get wrongUse tracing paper and hold a pencil on the corner dot while you turn, so that corner cannot move.
Key word
- quarter turn
- a 90° turn, a quarter of the way round
Ready to use it?
- Turn a shape 90° or 180° about one of its corners.
- Predict where the turned shape lands.