I just watched J8 teach A5 and H2 about why an orange will or will not float. It was one of the dearest exchanges I've watched between sisters.
"Look at how deep the water is! You can touch it."
"Now see this orange? I'm going to put it in the bowl. You want to do it? Okay."
Eager fingers grabbed hold of the orange.
"Ooohhh! Are you holding the orange or is it staying up all by itself?"
They smiled and told her it they were not holding it.
J8 pulled out a peeled orange and asked what the difference was between the two oranges . . . at which point another child called for me and I reluctantly pulled myself away.
Watching my children teach one another is one of my greatest joys!