The New York Hall of Science museum is free on Fridays, from 2:00 until it closes at 5:00. We had a lot of fun visiting it when we were in NYC last week (or was it 2 weeks ago?).
The kids liked climbing around on the mock-up of the Alvin submarine, and "programming a Mars rover," complete with real-time video camera. Lots of cool things to see and play with and learn from. We really enjoyed it.
One blip in the experience was a live demonstration of the principles of flight, in which we learned the amazing fact that a helicopter's blades rotate one way when it's flying up, then suddenly rotate the other way when it descends.
That is so not true. It is painfully not true. In fact, it hurt my ears to hear the otherwise respectable demonstrator say it. Just try to imagine what helicopter flight would look like if it was true.
Gravity does a fine job of pulling a helicopter down, thank you very much. No need to reverse the blades (which typically run at 120-400 rpm's!). Just slow them down a bit, and you'll find your altitude drops quite nicely. When I explained this to the presenter (afterwards, and discretely), asking if perhaps it was a misstatement, she insisted that's what the script says. Then I got a bit firmer (but still polite) and suggested she look it up to be sure.
It's not her fault - it's the fault of whoever wrote the script. Whoever it was apparently decided to just start making stuff up. It's fun to make stuff up, I know, but when you're writing a script for a science demonstration, it's probably important to not completely abandon fact.