I am planning for Mini sports day - go to the park with some basic sports equipment such as a soft ball, skipping rope, plastic set of skittles or badminton racquets and shuttlecocks. Take turns to challenge each other to games, and keep score. Organise simple races between the children, for example weaving in and out of trees along a certain length of the park, a hopping race, a three-legged race or an obstacle race. These work best when there are several children, but if there's a wide age gap you can give the younger children a head start.