Pooh Sticks

I don't know if that's what this game is called, but it's what I first called it and what J's uncles first said when they realized what we were playing.  The idea for this week's science came from Winnie the Pooh (I don't remember which one - they all blend together).

Background:
We were waiting around Ashland while J's daddy, uncles, and gpa went mountain biking.  After about an hour of playing in the park, J got anxious.  We went on a walk where we met a very odd man who gave J a stick.  We graciously accepted the stick but by the next bridge didn't want more to carry, so we showed J what happens when we throw the sticks over the bridge and into the water.  We then spent the next hour gathering sticks and leaves and tossing them off of the side of the bridge.

Topics covered in "Pooh Sticks"
Fluid dynamics/mechanics - flow of water.  What happens to the sticks in currents or around obstacles like rocks?  How do different items (ie leaves, rocks, sticks) react differently to the water.
Transfer of energy - things falling from bridge - transfer of potential (things "potentially" fall) to kinetic energy ("kinetic" is a fancy term for motion - so once it's falling it has motion and kinetic energy).
Trajectory motion - throw things off of the bridge.  Can you hit targets right off the bat?

Games
The original "Pooh Sticks": pick unique sticks per person.  Have everyone drop them off the bridge at the same time (drop them so the sticks end up going down stream and under the bridge).  Run to the other side of the bridge and see who stick wins the race under the bridge.
Targets: who can get their stick to hit a rock (or other target) after you throw it in the river?
Different objects: try throwing different objects into the river.  Note how each react.
Find the coolest stick!: the name says it all and if your child is like mine, it will take up to 15 minutes of time.
Name colors of sticks/leaves/rocks/anything you see off the bridge: colors are a very small portion of our electromagnetic spectrum.  Why not start nerdying up your child now getting him/her to memorize names and wavelengths?  I'm only somewhat joking.