I was watching a Nova special yesterday on all the people who had been involved in discovering the science that led to the fundation of Einstein making his 5 groundbreaking discoveries, including E=mc2, and only years later, some German lady whose name I already forgot (bad me) was able to deduce that they had split Uranium 238/93 by looking at the mass that had been lost in the byproducts, converting that into energy with that formula, and finding 200 million eV, which is the strength of a neutron-neutron bond IIRC.
Anyway, it occurred to me, that if I would somehow end up 100-200 years in the past, I would not actually remember a whole lot of everything I was taught in math, physics and chemistry during all my years in school. Ok, I remember uranium 235 and 238 (rich), but didn't even know its atomic number (necessary to know the proton/neutron split), 93, or forgot about the 7 planes electrons orbit at. Don't ask me about maxwell's equations, much of anything on electromagnetism (at least I know that they're linked, which wasn't know at the time), and I would quite struggle to compute any differential equations, matrix multiplications, differentials, or dévelopement limités .
All in all, I'd be fairly useless 200 years ago, if I didn't get to bring my HP48SX, its library of all physics/math/chemistry equations, and a set of fresh batteries. Shame, shame...

Eh, at least I know the sun rotates around the earth, and that we have to send ships filled with hydrogen to refill it once in a while, that's already one thing :)