Maybe you need something that will keep your grandson busy ... like this:

My son was pretty quiet back there in the trailer most of the time. But he did manage to poke a stick in my spokes on a 25 MPH descent. The last thing I heard was the sound of the stick end-over-ending down the street. I got out and noted that the trailer had apparently gone sideways and skidded down the street, grinding off a lot of the plastic knobs used to assemble it together. It uprighted itself just before I came to a stop. Our colloquy:
"What happened? Did you put a stick in my spokes?"
"Yea, we cwashed."
"I don't suppose I have to tell you to never do that again?"