Check out these sites for additional help in various STEM Subjects:
Khan Academy – Videos and lessons in math up to Differential Equations, Chemistry, Biology, Physics, Engineering, and more
Wyzant – Lessons in math up to Calculus, Physics, Chemistry, and Biology
Math is Fun – Lessons in math up to Calculus and Physics
Math Portal – Lessons in math up to Linear Algebra
Paul’s Online Math Notes – Lessons in Algebra, Calculus, and Differential Equations
the Physics Classroom – Lessons in Physics
Hyperphysics - Online Tutorial of Physics Subjects
Physics 24/7 – Example problems from different concepts in physics with solutions
Splung – Lessons in physics broken down by concepts