This is a STILL image.

It is NOT a movie.

Task B

This shows a variant of the original task, where ABCD is now a parallelogram rather than a rectangle.

As before, it helps to consider the diagonals of EFGH. Not surprisingly, the relationship between AB and AD and EFGH is similar to before, though perhaps less obvious.

EFGH turns out to be a rectangle this time (rather than a square).
This might seem surprising at first and it is worth asking students to explain why.
[In some ways this is easier than explaining why EFGH is a square in the original task, for the very fact that it is less obvious ...]

You can explore the task further using the interactive worksheet JAVA-2, or the slightly more structured worksheet JAVA-3.

On the final three pages we show three more related tasks: PS-1 PS-2 PS-3

a high-res pdf file of this new GEOaa-zz task