Summer is a wonderful time for kids to indulge their creativity. Mine like to work on plays with their friends. If they like acting, encourage them to make a play.
They can write it down or not. My kids prefer to do it all from memory – I’d get a lot of resistance if I wanted them to write it all out. But let them go about things their own way and they’ll work it out.
One of the great parts is how much cooperation making a play requires. There may be arguments, but if the play is going to work out, they have to come to agreements or learn to improvise around each other. Either one can be interesting.
Just be ready to be an appreciative audience at some point. If the kids are happy with what they’ve done, they will need an audience.