How to remember what your lecturer teaches you?

Im having a really hard time at the moment with the following subjects, chemistry, biology, physics and maths, I just can't seem to remember anything were taught, I go over everything the lecturer says I take notes down as much as possible but none of it helps as soon as Ive written down some notes I forgot what I wrote straight away, everyone else in cl seems to be always understanding what the lecturer is on about, when Im there frustrated, wondering how on earth do they learn so fast? What can I do?