"Get in it?"
"A new wagon!"
"Can me use it?"
"It's heavy! I'm pulling hard!"
There was much climbing, negotiating space, pushing, pulling. It was immediately obvious that the trouble was that there was no handle. "It broke" SC explained to everyone, showing the handle that we eventually found. Someone had attached a rope to the front and various ways of pulling were tried. It was very heavy, especially with someone inside, so often the riders were left abandoned. Everyone took turns being the rider, pusher or puller as they worked on conquering this new toy.
At one point the wagon was really rolling. SC was pulling T up the hill near the front of the yard. It went up a bit then SC said, "That make me nervous." And stopped. GW quickly came over, "Me get in too! Go for a ride with T!" He worked for a while, talking to T and climbing on until he figured out the best way. SC tried to pull again, but it was "too heavy."
All of this experimentation with each others space and navigating and controlling a large, awkward piece of equipment is right up their alley right now. The big climbing and rolling draws them in and the challenge and awkwardness pushes them to use their burgeoning problem solving skills. The biggest trouble with the wagon was that it couldn't be pulled in a straight line, so they quickly realized that pushing worked much better.