Double-click on the movie to PLAY.

Click once to PAUSE.

RELOAD the page or double-click to return to the START of the movie.

Movie A3

In this movie, side AB stays constant this time, while the length of side AD changes, from 11 units long down to 0 and back again. Before showing the movie, ask students to predict what will happen to the square as AD starts to decrease.

On the next page we show what is essentially the same movie, but with pauses at salient points. You might prefer to show that movie first.