Teaching Science--One Fact

If you could teach your kids one single fact, what would it be?

For science, I would want to be sure my students know that each nucleus wants to have 8 electrons in its outer shell.

This may seem kind of cerebral and not useful (Academic is an accurate word to use to describe something that has no practical value), but really, that desire of atoms to have eight electrons in the outer shell is an engine that drives pretty much all physical processes in the universe.

How molecules respond to each other is determined by the valence of the outer shell. All chemical reactions are based on this.

In more complex high school and college levels, it can be presented as a potential energy problem. As a chemical reaction takes place, the electrical charge (or partial charge) of one molecule causes the other molecule to respond. As they get closer to reacting, the potential energy becomes greater, (just as a magnet gets stronger the closer it is) and just before they react and redistribute their electrons, the potential energy is great. Then, after the reaction, the new molecules(s) will be in a stable configuration, which means they will have a low potential energy.

Of course, everything in nature wants to be equal. You have heard that nature abhors a vacuum; well it's true. Nature wants molecules to be evenly distributed, thermal energy to be evenly distributed and electrical charges to be neutralized. In other words, the laws of physics seek out high potential energy situations and brings them into a low potential energy solution.

Can you think of any examples of this? (A rock rolls to the bottom of the hill, and there it stays--how about that?)

Think of any physical process and you can reduce it to the desire of atoms to have eight electrons in the outer shell. (This does not include plasma inside the sun and stuff like that. Plasma is a mess of disassociated subatomic particles that can't organize because of extreme thermal energy. But it does apply to all biological functions.)

Now I have to think of one thing I would present if I could teach history with only one fact or one item.
Hmmm....

What would you choose?