I need help figuring out how to select my classes so I can study for my SAT's.

Hello Connor,

Khan Academy has an SAT study course for all four sections (math w/ and w/o calculator, reading, and writing & language). 

https://www.khanacademy.org/mission/sat

However, if you do not find that helpful, I would suggest these courses:

English

grammar         https://www.khanacademy.org/humanities/grammar

Math

basic geometry   https://www.khanacademy.org/math/basic-geo 

pre-algebra         https://www.khanacademy.org/math/pre-algebra

algebra basics    https://www.khanacademy.org/math/algebra-basics

algebra 1            https://www.khanacademy.org/math/algebra

algebra 2            https://www.khanacademy.org/math/algebra2

high school geometry     https://www.khanacademy.org/math/geometry

high school statistics      https://www.khanacademy.org/math/probability

A lot of what is in these courses will be on the SAT.  Also, I do not think the SAT has a science section; the ACT however has one.

Hope this helps.