I can understand it, but it's the rearranging of formulas I struggle the most with. There are times where I don't notice things either, like today we were told an 8mm ball takes 0.5 seconds to fall 0.2m through oil, but I thought it said 8m... (well he said the equation out loud, and I thought he said metres instead of milimetres) Plus there's loads of ways to reach an answer, and there's only one correct one.
Meh, I guess the reason I don't ask is that nobody else asks, and a few also don't understand (because sometimes i've asked them what we're doing, and they say they don't know...)
All lame reasons, but I just don't like asking for help.