ACT Academy - Create a free account. Practice for the ACT, watch videos to help with difficult concepts, and take practice test to prepare for the ACT.
A resource to help detect, prevent, and avoid classroom plagiarism.
Offers help on 10 high school subjects, such as Biology and U.S. History. Excellent written, audio, and video tutorials have review questions sprinkled throughout. You’ll also find interactive aids for 100+ textbooks.
A great resource for high school math. Concepts of Algebra, Probability, Calculus, and other subjects are explained clearly and thoroughly. The search engine tracks down topics quickly.
This site for grades 9 and up teaches by examples – you’ll find tons of problems and step-by-step solutions for Trigonometry, Calculus, and more. Practice quizzes let students learn by trial and error.
The Purdue University Online Writing Lab (OWL) offers 200 free lessons and guides for grades 7 and up. You’ll find advice on structuring a thesis or essay, doing research, and avoiding composition pitfalls
The superbly organized site gives tutorials and excellent multimedia examples (video and audio) that demystify concepts of physics. The sample problems are illustrated and clearly explained.