Yeah, let's take everything out of science classes that no one has ever observed. Like for instance photosynthesis (nope, the actual hypothesised chemical reactions have not been observed, only the effects) krebs cycle, sub-atomic particle theory, most meteorology, thermodynamics (no system both truly closed and discretely observable exists, plus the theory is really only statistical in the end), etc, etc, etc.
We'll still be left with "facts" such as "the sky is blue" and "the grass is green" (but just with no explanation of why).
Get rid of Avogadro's Number. I mean really, who has ever counted 6.022 x 1023 atoms of Carbon-12 anyway?