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Optical aberrations in amateur telescopes. Includes principles of physical and optical imaging with detailed review of primary aberrations. Also, aberrations in popular reflecting, refracting and catadioptric telescope objectives, telescope eyepiece and human eye.

PhysicsLAB is an online high school physics program being implemented at Mainland High School in Daytona Beach, FL. Students receive all of their daily assignments, labs, resource lessons, worksheets and on-line tests off of the website. Daily Schedule pages, calendar and course syllabus are powered by LearningXchange, a databased management system.

Tutorvista provides Online Tutoring, Homework Help, Test Prep for K-12 and College students. Connect to a Tutor Now for Math help, Algebra help, English, Science

Online Dictionary - Multiple dictionaries including: English dictionary, medical dictionary, legal dictionary, financial dictionary, computer dictionary, thesaurus, dictionary of acronyms and abbreviations, dictionary of idioms, thesaurus, Columbia encyclopedia, Wikipedia encyclopedia, Hutchinson encyclopedia, examples from classic literature, pronunciations, word browser, glossary. Free access

An expanding collection of freely available, interactive Demonstrations in math, science, and many other areas--at all levels from elementary education to front-line research.