You’re wanting to take note of the extraordinarily important director who is involved here. Brault has fashioned something like Rossellini for kids, but this time with a scientific subject. Maybe we should make that David MacAulay, and then with photography that you might see in an Eric Rohmer film. The situation here is really set up, but it appears to be fully improvised within that set-up. The result is charming, and faintly moving. The narrator tells us why. The oldest mechanical principle is fresh and even beautiful to the person who discovers it for the first time. The kids proceed to demonstrate. Eager, willing boys. Stunning girls! They lead us up to the point of a scientific insight, or demonstration, and then stop to let us figure it out for ourselves.