Conentrarting first of all you need to have your mind set on what you are doing, i find you either shut off everything around you "mentally" meaning ignoring your surroundings and do what you have to do.
Also what ever your concentrating on you need to think about how badly you want it like in an exam how well do u really want to do i find that helps.
As for absorbing there are two ways i was told people take in information some people need to visualise th einformation they are learning so for example when you study write your notes in coloured pens so the heading a colour the actual information in another colour (doesnt have to be pink green just regular black and red and blue

).
others just need to hear the information once and they can take it all in