Blue Angel Magic

Today’s edition of the Wall Street Journal has an interesting article on science education in Science Journal by Sharon Begley (by subscription only). Here is the text of a letter I emailed her.

Of course scientific education in America is pitiful. But the choice may not be between “discovery learning” and “direct instruction”. More likely the solution will be a combination of “Aha! moment discovery” and interactive direct instruction. This is a much more sophisticated technique. Let‘s demonstrate the “Aha Moment” by an example. What is needed is to teach on a foundation of the knowledge the child has accrued in daily life. Then by challenging their ideas, impressions and misconceptions (the interactive part) guide them (the direct instruction part) to a greater understanding of the science.

Here in Chicago we have the annual Air & Water Show. It is a perennial crowd favorite that climaxes with a performance by either the Navy Blue Angels or the Air Force Thunderbirds. It’s lots of fun and gets one million spectators. Virtually every kid has seen the show. That is the only life experience they need.

Now the object is to teach them about how an airplane can fly despite being heavier than air. This is a common source of wonderment. So here is the pop quiz for science teachers everywhere. How do they fly upside down? We’ve all seen them do it. The conventional wisdom is that the bottom of the wing is flat, the top curved so the airflow has a longer distance to go in the same time. This increased velocity is derived by converting the static pressure above the wing into dynamic pressure (the Bernoulli effect). The different static pressures above and below the wing create a differential pressure that results in lift. Ergo the plane can fly. Sound familiar? Well don’t try that nonsense on my grade school pram sailors! They’ll point out that when the plane is inverted the curved side of the wing is down. By your logic, the inverted “lift” and gravity should combine to force the plane down into the lake. But not those Blue Angels & Thunderbirds! How cool they must be to have this magic at their disposal. Aha, teach. Gotcha!
You don’t think I’m going to spoil the magic by giving you the answer do you? At least not before you’ve tried to figure it out. Turn in your homework tomorrow.