No, we did not make Ronan draw free body diagrams with his crayon set, but we did have "fun with physics" thanks to a soap-box car track at Ronan's (hopefully) future elementary school. Ronan was intrigued by the aluminum panels and the spring-loaded release mechanism; this curiosity morphed into delight after he rolled a tennis ball down the track.
The switch was to test the effectiveness of 'lashing' the tennis ball to see if that would encourage it to go faster. Alas, no such luck.
I tried to explain potential & kinetic energy but Ronan seemed more interested in stylistic release approaches (see photo) and figuring out why the tennis ball would sometimes careen off the track (there was a protruding bolt head in some of the tracks that would send the ball flying). Sadly he also showed no interest in learning about moments of inertia. Perhaps we'll need a gyroscope to get him to ask, "how does it do that?"
This is how we do it... with *style*