1) Science is a Process, Not a Collection of Facts The essence of science, broadly defined, is that it is a systematic approach to figuring out how the world works:
1. look at the world around you
2. come up with an idea for why it might work that way.
3. test your idea against reality.
4. tell everybody you know the results of the test.
2) Science is an essential human activity. Science is essential to our nature, because at its most basic, science consists of looking at the world and saying "Huh. I wonder why that happened?" Science is applied curiosity, and there's no more human quality than that.
3) Anyone can do science. Science does not require innate abilities beyond the standard-issue human genome. You may not understand a particular set of facts produced by science, but see point #1 above: Science is a process, not a collection of facts. You won't necessarily understand all the facts of a particular science outside your own field of expertise-- I don't understand microbiology worth a damn-- but if you have the brain power necessary to function as an autonomous adult, the process is within your grasp.
So, what do you think everyone should know about science?