If you feel determined - and you **really** want to study over the summer before starting college, here is my advice.
Go to Barnes and Noble (or Amazon) and buy these books:
(1) AP Chemistry by **BARRONS** Review
(2) AP Physics B by Princeton Review
(3) AP Calculus AB/BC by Princeton Review
(4) AP Biology by Barrons Review
If you study these books over the summer break - you are SAVING yourself from so much pain in college. When going through these books - skim over the reading, and focus on the PRACTICE PROBLEMS in each book. The only way to learn science is by solving problems.
Remember that the MCAT has Physics, General Chemistry, Organic Chemistry, and Biology on it - by studying those books that I recommended, you are preparing yourself for both your classes in college and the MCAT or DAT (the DAT does NOT have physics on it).
Remember - that medical schools / dental schools require you to finish a specific number of classes - by studying those AP Science classes, you are basically preparing for your college classes- that is why I recommended those books. Remember that when you walk into your chemistry class as a freshman - you are competing against other students who have already taken AP Chemistry - and AP chemistry is EXTREMELY difficult compared to college chemistry - which is MUCH easier.
The books that I recommended might seems overwhelming - because they are so long, but the easiest way to go through those books is just by solving the problems inside - by solving problems, you are learning chemistry, physics, calculus, and biology.
Learning the sciences in college is not done through reading the textbooks that college professors recommend (those textbooks are as thick as an encyclopedia - it is very hard to read through a chemistry book in college) but the only way to learn the basic sciences is by solving problems. Solve as many problems as you can.
Invest in those AP books - and they will save you so much trouble and pain in college. The depth and detail of those AP science classes are much more complex and harder than the science on the MCAT or DAT. So if you study those AP science books - you are preparing yourself for both the MCAT/DAT and your college classes.