People retain knowledge differently, For me recalling works great, I know a lot of people like flash cards they work well maybe try Quizlet. You can look up other peoples learning styles and give that a shot. I'm hoping that you did take notes so you can review them. I personally didn't know there was a prep class for the DAT, I've heard most people using "Dat Destroyer" and a bunch of other studying methods. Either way GC,OCHEM and Math are huge factors in your scoring. Id say you need to get your confidence up and start studying around 5 hours a day with taking a bunch of notes until you feel confrontable. I don't know your situation for sure since you have took it before and got a 15 maybe get a tutor or another means of studying. If anyone would like to add on go for it. Best of luck and let us know how you do.