They’re very hard to forget...
Just string a rope between two trees
And throw the ball across the net!
Find a suitable space between two trees, poles or walls. Stretch the rope or net between the two points at a height just taller than the children. There should be enough space either side of the net to run around without stepping on mom’s flower pots or scrapping your arm off the wall!
Once everything is in place you divide in to teams, with one team on either side of the net. You throw, push, bat or punch the ball over the net. Anyone who doesn’t catch the ball or drops it loses a point to the other team.