what they do at baseball tryouts?

my son played little league a while back, when he was 9. however, he kind of outgrew it up until about last year (9th grade) he told me that hes decided to try out for his high schools baseball team. i know its a long shot that he'll make it, since he hasnt played in a long time. either way, im trying to get him prepared for the tryouts. what things do they do at HS baseball tryouts? what should i practice with my kid?