A team game. Make a chute using individual sections of guttering on strings to pass ping pong balls from one bucket to another - against the clock
600mm cut lengths (doesn't have to be precise). Drill two holes each end at the sides, thread string through and knot over the top of the guttering, leaving enough space for a ping pong ball to run through. This forms a harness (it goes over your head and rests at about waist height). Two buckets. Many ping pong balls. Stop watch or phone timer.
Working in teams (5 in each is about enough) the children are each given a piece of guttering. Wearing the string over their shoulders with the guttering in front of them, they have to line up side by side and form a guttering cute. Place a bucket with ping pong balls at one end of the line and an empty one at the other end. Now only holding the string NOT touching the guttering with their hands they have to transport the balls one at a time, from one bucket to the other. Sounds easy but it really isn't until they start working as a team!