The boys look like they're in 5th grade or so...the girl looks like she is probably in 3rd? They aren't infants, and their dad obviously works in this field. This was a great opportunity for them to see what dad does beyond sitting in a lab all day.
When I was that age I would have been ecstatic to see what my dad did, doubly so if it had had something to do with science.
I think this shows (and I'm probably wording this poorly) that all scientific facts can be verified. We (mankind) have built up this body of knowledge, and if you are determined enough you can validate each link of knowledge in that chain to determine the truth.
Knowing that a plane flies vs. knowing how it flies is a valuable thing indeed.
Kudos to this dad for encouraging curiosity in his children. All too often this trait is squelched.
