Note that this page is aimed primarily at K-12 teachers. Those teaching at higher levels will find appropriate resources at Useful reference & subject sites for college students & teachers.
Online Masters in Education has created a list of the 100 Best Web Resources for Educators in 2012. It’s divided into preschool, elementary, middle, and high school.
The Guardian website has a section called the Teacher Network that "gives teachers access to 70,000 pages of lesson plans and interactive teaching materials", including a bank of testing material that you can use to build your own tests and deliver online or in print.
Edutopia has a "Schools That Work" site, where you can "Discover successful schools and strategies across the country -- and use their best teaching practices, training materials, and rubrics with your students". http://www.edutopia.org/schools-that-work
For those interested in the Waldorf approach to learning, a new website inspired by Waldorf Education provides age-appropriate movement activities and a number of articles.
Worksheet Library is a nicely done site by a group of teachers, with a large collection of free and paid worksheets for grades K-6
Happy Child, who have a lot of good stuff on their own account, also provide a list of links to various good educational sites
the Gateway to Educational Materials: a directory to high quality lesson plans, curriculum units and other education resources on the Internet (and you can specify that you only want free stuff)
A to Z Teacher Stuff: a directory of online resources for teachers
Charles Sturt University's Education Virtual Library is a great starting point to any search. You can specify your general educational level (primary, secondary, tertiary).
PBS offer a directory of lesson plans
LessonPlans4Teachers claims to have created the best lesson plan directory and search site on the Internet
a directory of Internet resources for the classroom, complied by the University of Otago, New Zealand:
"worksheet factories" - programs to enable you to produce customized worksheets - are available from Schoolhouse Technologies
Abiator's Active Classroom: a New Zealand teacher's site for his Year 8 class, with lots of resources in most curriculum areas, regularly added to
Education World offers lesson plans and professional advice to teachers (U.S.; elementary level)
Study Stack: flash cards in various subjects
Teach-nology offers a lot of resources to subscribers, but also has a number of free worksheets, worksheet makers, graphic organizer makers, and rubric makers
"About" have a good homework site for high school students. It's ruined somewhat by ads and sponsored links cluttering up the page, but the actual content is quite impressive. Make sure you keep your eyes on the left for the options available to you, and if you want to go back to a page, use the dropdown menu (click the downward pointing triangle to the right of "Back"), don't simply click the Back button (there's a couple of hidden ad pages in there that make you think nothing's working).
The BBC site is broken down into age-groups: Preschool; 4-11; 11-16; 16+. UK students can also find several revision guides for different exams (including a Welsh one, and guides for Scottish exams)
Kid Info calls itself a reference resource for teachers, parents and students, and seems to have an impressive number of links, categorized on simple, clutter-free pages. [American]
The "Middle School Cybrary" is a bit out of date (last updated 2003), but most of the links still work
"Teachers at work" is a New Zealand site, with thousands of reviews of educational web sites (categorized and rated).
Education Atlas is an extensive directory of education sites, covering early childhood through to college
Here’s a Web app for those who want to improve their vocabulary, or for teachers to recommend to their students: Professor Word – ‘a free bookmarklet that helps you learn new words while you surf the web’. It can be customized depending on whether your goal is to study for the SAT or ACT, learn English, or just improve their vocabulary. And if you’re a teacher, there are apparently several tools ‘coming soon’ that will help you find readings and monitor student progress.
English Companion is a community site for English teachers looking for help and ideas. http://englishcompanion.ning.com/
English Zone: grammar, spelling, vocabulary, advice on writing. Includes a section for teachers, with worksheets, lessons, quizzes, classroom games and activities, etc.
Oxford University has some free literacy and numeracy teaching resources at http://www.education.ox.ac.uk/research/child-learning/resources/ . They also have a number of special literacy and numeracy resources designed for deaf children.
Best of History Web Sites is " an award-winning portal created for students, history educators, and general history enthusiasts"; sites are rated for usefulness and accuracy
History Matters: "the U.S. survey course on the web". Designed for high school and college teachers of U.S. history
U.S. Department of Education has some good U.S. history resources for schoolteachers http://teachinghistory.org/
Genealogy for kids: article on how children can participate in genealogical research, with links to helpful sites
A teacher's guide to the Holocaust: An award-winning site about the Holocaust, packed with information, photographs, movie clips etc.
A visual sourcebook of Chinese civilization: designed to add to the material teachers can use to help their students understand Chinese history, culture, and society
A guide to K-12 Medieval studies: from the Labyrinth, a Georgetown University sponsored site on Medieval Studies, a list of links for students and teachers, including sample lesson plans.
The Online Reference for Medieval Studies is a serious academic site. However it also provides links for "those whose interest in the Middle Ages has been spurred by popular representations of the period in movies, television, and historical fiction", and these may be of use in the classroom.
U.S. History/Social Studies for secondary school teachers
The British Museum has an extensive site on ancient Egypt
Here's a specialized directory of web resources about voyages of discovery and exploration
Mathematics & Science
Math Worksheets Land, run by a retired (and now homeschooling) teacher, has thousands of free, printable math worksheets, covering a wide array of topics, from kindergarten to high school, and all aligned with the core curriculum. A nice resource.
Carleton College’s Science Education Research Center has produced a resource on "Guided Discovery Problems" and how they can help teach science, together with some examples.
The University of California Museum of Paleontology has developed a website to help teachers get young people interested in science. Understanding Science aims to be “a fun, accessible, and free resource that accurately communicates what science is and how it really works."
Practical Physics, created by the Nuffield Foundation, presents “a collection of experiments that demonstrate a wide range of physical concepts and processes” for teachers of physics in schools and colleges.
The American Geosciences Institute have an array of curriculum materials for all levels, from elementary to college.
Computer Science Unplugged is a YouTube channel containing 50 videos aimed at communicating computer science concepts to students of all ages.
Here’s an extensive list of algebra resources for high school students (Thanks to Alyssa Britton’s class at Jean Massieu Academy)
Frank Potter's Science Gems apparently has over 14,000 science resources sorted by category, subcategory, and grade level.
There's a list of math & science sites here (thanks for this link go to Amy from Ms Ward's class)
Get the Math as about practical applications of algebra. It uses video and interactive challenges, and is aimed at middle and high school students.
An elementary teacher told me about the list of math sites here, but I think some of them would be of interest to high school teachers too. I was particularly taken by the site showing how math is used in different jobs.
The Khan Academy is chock full of instructional videos, mainly on math and science topics. http://www.khanacademy.org/
The American Association for the Advancement of Science site presents 600 items that teachers can use to test middle and early high school students' understanding in the earth, life, physical sciences, and the nature of science. Importantly, it also tests for common misconceptions. http://assessment.aaas.org/
Here's one I want to urge on any science teachers, believing as I do that every citizen should understand the basis of scientific thinking (and particularly the scientific meaning of the word 'theory'!), something that apparently so few (and so few teachers) do. Peer Review Education Resource provides several lesson plans to help teachers understand and explain how real science works.
LearningScience is an open community for sharing tools and resources for teaching science.
Maths Worksheets World, which has over 12,000 K-12 math worksheets, lesson, homework, and quizzes. There's also free math worksheet makers to help you make your own. http://www.mathworksheetsworld.com
Math Worksheet Center claims to offer over 8000 math worksheets for K-12 students (5 - 18 years)
Lesson Corner: a new website where teachers and homeschooling parents can generate math worksheets. Nicely done
Teachers of younger children might find the basic-operation games at http://bigbrainz.com/ an exciting resource.
Mathcasts provide screencasts for mathematics, math movies if you like
Math Forum: search the Internet Maths Library by grade level
Go math: online maths help with interactive quizzes and tutorials http://www.gomath.com/members/test/tutorial/body.html
an eclectic mix of sound, science, and Incan history intended to interest high school students in Euclidean geometry
Mathematically Correct is a U.S. site "devoted to the concerns raised by parents and scientists about the invasion of our schools by the New-New Math (The current revolution in mathematics curriculum, akin to the Whole Language experiment, that emphasizes group discussion, essays, calculators and guessing and de-emphasizes basic skills and direct instruction) and the need to restore basic skills to math education."
Worseley School Science Files: science and math resources for all grades from middle elementary through senior high school
Teachers might find the Art Institute of Chicago's course exploring the relationship between science and art useful and inspirational.
NIH Office of Science Education has lot of resources for teachers
Super Science Fair Projects for help and inspiration with your science fair
ASPIRE - Astrophysics interactive labs for teachers
Backyard Brains has "exciting and affordable entry‐level Brain Recording Kits that provide the ability for students of all ages to learn about neurons"
Physics teachers might find some useful resources at http://www.aapt.org/Resources/teacherresource.cfm
Science, Optics & You - teacher resources, student activities and interactive java tutorials in light, optics and color
Nottingham Trent University has some nice science resources for primary, secondary, and "post-16" levels. http://www.ntu.ac.uk/cels/outreach/Resources/index.html
The Exploratium has a "Cool Sites" archive at:
Spacelink: instructional materials from NASA
Ocean Sciences Teacher Resource Center
NOAA Ocean Explorer has lesson plans available
Biotech-Adventures: an educational web site designed to present the factual information regarding biotechnology in a way that will entertain both students and adults.
The Earth Science World ImageBank has photographs of all aspects of Earth Science, climate data from weather stations around the world, and an interactive game to discover oil
Geology.com has some useful resources for teachers, with teaching ideas, articles, and maps linked to satellite images
Hands on CERN is aimed at teachers and high school students studying natural sciences. Its purpose being to increase understanding of the most fundamental processes inside matter, and to explain modern research about particle collisions.
Howtoons are one-page cartoons showing 5-to-15 year-old kids "How To" build things. Each illustrated episode is a stand-alone fun adventure accessible to all, including the pre-literate.
The Missouri Botanical Garden has quite a nice site on biomes and ecosystems
National Public Radio have a " Kids Connection" - linked to a weekly radio program on science news, it offers discussion ideas, activities, selected resources, and related science standards, linking programming to the classroom curriculum (middle school).
Understanding evolution is a website for teachers, aimed at explaining evolution, pointing out relevance, misconceptions, pitfalls, and so on.
TeachEngineering has "teacher-tested, standards-based engineering content for K-12 teachers to use in science and math classrooms" at http://www.teachengineering.org/
The Biotechnology Institute has resources for high school science teachers wanting to introduce their students to biotechnology http://www.biotechinstitute.org/teaching-resources