The trajectory schema: Which way will you go?

Here is a girl.

She launches a paper aeroplane across the living room and it is fun.

It dips, it swerves, it flies.

It cuts through the air. Delighted, the girl chases along behind.

At last, it lands gently on the rug.

But the game doesn't stop there.

Back to the start she goes and the plane takes off on another flight.

How many times does she do this? Who knows? Who cares?

It's all so interesting. The clock stops. Time stands still.

This is the trajectory schema. For many under 5s, it can become a fascination, an obsession - or even a compulsion.