What a great way to get some stomach exercises!
Each child will have their own cone that they will put behind their head.
Children must sit up and grab a hoop and lay down and lay it around their friend's hoop.
Safety wise, kids should make sure they don't hit their classmate with their hoops.
I could see this running two ways:
A competition to see who can get their hoops down and back, or working cooperatively for time so the kids just continually passing the hoops down, passing them back, and then keep going.