Khan Academy
This organization has resources for every course and level. It mostly produces short lessons in the form of videos.
Bozeman Science
This website has a wonderful collection of science videos, slideshows, and resources for advanced high school students and younger college students. As all the resources are categorized by course (including several AP courses), this is a great resource for anyone tutoring a student who needs help in a specific class and wants help finding resources that match the curriculum.
Chemistry Sky
This site, created by a former chemistry teacher, has a vast collection of chemistry practice problems, study questions, and links to further resources.
Brightstorm
This website provides easy-to-follow chemistry videos. These videos are great for high school chemistry, AP Chemistry, and College level Chemistry.
Crash Course
This website provides easy-to-follow videos on a multitude of science subjects.
MHS AP Chemistry Barry
The website is an amazing resource for AP/College Chemistry. The website is divided into units that include notes, class problems, practice exams, and AP long answers.
