You might choose to begin with a whole class activity revisiting the points of the compass - perhaps having all the children facing one direction which you denote as north, and then turning to the west, south, north-west etc.

If your children have not done much recording of journeys before, you might then ask one child to come to the front and be given instructions to move. For example: take five steps north, turn to face east, take five steps, turn to face south, take five steps. Ask the class how s/he could get back to the start. (Where was the start - did we mark it?) Model the journey on the board, perhaps using a square grid to help the children to see that the directions form three sides of a square.

Gather the class together and ask for solutions and methods of working. Question them about how they know what the dimensions and directions are for the return journey - listen for explanations that include parallel, parallelogram, same angles etc.

(Most children will not question the numbers $20$ and $50$ - they will assume that this is the distance. If it is appropriate you may want to question this and begin to make links between the time taken and the speed travelled. It's difficult to show time on a picture but if the bird travels at the same speed for the whole journey then the time and distance travelled are directly proportional to each other. Progamming Beebot or Roamer may also bring up such questions.)

Shall we show where north is?

How do you know these lengths (on a parallelogram) are the same?

You may wish to offer children the opportunity to make up their own questions in the same vein, and post them somewhere central for others to try. You could also try some 'What if ...?' questions and encourage the children to make up their own of these too, for example, what if the speed changed and the bird flew back twice as fast?

For some pupils this activity might also be an opportunity to experiment with LOGO (freely downloadable from http://www.softronix.com/logo.html ).