I really need some help urgently. Pretty please.

In three weeks time, I've got to go and lead a reception class or a year 3/4 class (I'm not sure which it is) for an hour in a PE lesson. It's for a junior sports leader award which is completed by the end of the year. One of my PE teachers will be watching me and judging me.

What I need is some ideas of what I can do with both classes taking into account their age and health and safety. According to our PE teacher 4 year-olds can't catch, so as you can see it has to be very aged focused. Any ideas will be really appreciated. I have an hour to fill.

Thank you so much.