Any other formulation is disingenuous. We don't know that the Earth is the center of the universe. Hell, even Elon Musk said we might be in a simulation a few days ago!

Ideally, you should also tell the kids which evidence suggests a theory.

Elon Musk: The chance we are not living in a computer simulation is 'one in billions'

http://www.independent.co.uk/life-style/gadgets-and-tech/new...

"Knowing" is generally considered to imply that we think something is beyond reasonable doubt. If you can only speak of knowledge in the sense of logical entailment, the word would be useless because then nobody knows anything. Words like "maybe" and "possibly" would also become useless, because they then apply to all knowledge. A distinction that doesn't distinguish between things is not a useful distinction to make.

Reasonable doubt is a legal term, not a scientific one.

Are we not the center of the observable universe?

Most of the observable universe is in front of you, so you're not in the center of it.

I'd support that.

Elememtary textbooks contain almost exclusively the seminal theories that we are very sure about. If we expressed our certianty there, kids might get the idea that all of science is similarly so.

In science, "the evidence suggests..." is a very high seal of approval. I'd place more emphasis on making them understand that than I would on adding a few nines to their certianty that the earth is round.

Can't say I know what the US curriculum is mostly like, but I was taught about the Bohr atomic model before learning about how they figured out why it wasn't exactly right and we talked about how Newtonian physics was superseded by relativistic physics. There are better ways to express the scientific ethos than to just prefix every statement with "maybe".

I would accept one that cited the IPCC report noting a warming hiatus for the last 15 years :)