Twenty-Seven Revolutions

The first thing I’m accomplishing on my  birthday is publishing this post. Since I’ve been born, the Earth has revolved around the Sun twenty-seven times and rotated on its axis 9,862 times (including leap years).

The terms revolving and rotating are frequently used interchangeably, but technically there’s a difference: rotating is motion around an internal axis, while revolving is motion around an external point. Spinning in place is rotation. Walking in a circle is revolution. While I haven’t really considered this point before just now, it means that “revolving” doors would more accurately be called “rotating” doors.

Demonstrating rotation and revolution for my physics students was fun. I’d spin in place to show rotation, then walk around a stool to show revolution. Then I’d spin while walking around the stool to illustrate the motion of the Earth around the Sun. There’s nothing like watching your teacher make herself dizzy to help you remember a concept.

One of the things I love about teaching and learning science is the a-ha moment you get when something clicks, and those moments happen so much more often when you’re seeing or doing something as opposed to just reading or hearing about it. I could’ve just recited definitions for my kids, but it was so much more effective to make myself look silly for a minute. Thousands of books and websites will tell you how electric charges move and interact. Reading all of them won’t replicate the experience of rubbing a balloon on your hair, then sticking the balloon to a wall. I’m going to conduct (see what I did there?) that activity at the next kid’s birthday party I attend.

Or maybe I’ll get some balloons for my own party. You’re only as old as you feel.


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