WikiTeach has been launched! 
WikiTeach was launched by the writer of this proposal in April 2006. Check it out at www.WikiTeach.org. Another site to share Lesson Plans using a mediawiki is www.lessonplan101.com. The goals of the site are a little different then wikiteach.org. Check it out.
What is wikiteach? 
Wikiteach is a proposed encyclopedia of classroom lesson plans and projects, a bag of tricks for teachers.
Who would use it? 
Teachers need an encyclopedic clearing house of teaching ideas, categorized by subject and by grade level. Each subject should be broken down into topics and further into lesson plans. For example, a math teacher who wants to teach fractions would select the subject "Math," then the topic "Fractions," and then a list of lesson plans would appear. She could sort the lesson plans by selecting a grade level -- maybe 4th grade, or maybe remedial college math. Finally, she could use a keyword search to further refine the list.
Why is it needed? 
Teachers spend much time and money improving their lessons, projects and teaching methods. They typically look to books, other teachers and websites for new ideas, but these resources are limited in several ways. Textbooks are usually dry and bureaucratic, so they don't bring the special flare that teachers need to inspire learning. Alternative books can be useful, but they usually encompass more than the single lesson a teacher wants. S/he has to buy a whole book to get one activity. Other teachers are often too busy, dealing with their own lessons and grading, to offer much help. Websites can be useful, but they tend to be limited to a handful of contributors and a few ideas.
Why should Meta-Wiki host wikiteach? 
Wikiteach is an important step toward WikiMedia's goal of spreading knowledge because teachers spread knowledge for a living. They are an organized, vocal group who would enthusiastically support the goals of the Foundation through a venue like wikiteach.
Wikiteach would compliment wikipedia and wikibooks, because lesson plans often refer to articles and books, even though the lessons stand on their own.
The lesson plans must be organized in a common-sense manner to be of any use. The best way to do this would be to divide the material by subject as it is in school -- Language, Science, Math, Music, Art, etc. Then the subjects would be divided into topics. English would be divided into grammar, literature, essay writing, etc. Finally, the topics would be labeled by grade level -- preschool through post graduate. In this way users could easily find the lesson plans they need.
A user wishing to add a new lesson plan would be required to specify a subject, a topic, and a grade level. She could select a subject from an existing list, or she could create a new subject. In case her lesson fit into more than one subject area, she could select more than one subject. She would then select a topic within each subject area or create a new topic. Finally she would select a grade level -- preschool through post graduate.
Users should also be encouraged to post little teaching tricks, even if they lack complete lesson plans. Sometimes it's the little things that can give some snap and flavor to the content, allowing students to really enjoy a lesson.
Additional features could include, official curriculum standards for each of the 50 States, a classroom management section, and theories of teaching.
Each subject and topic would have an overview description and links to Wikipedia articles, so readers could explore the basic ideas behind the content.
Similar Websites 
- Discovery Channel - Not a wiki. Content is good but there aren't enough lesson plans.
- Educational Realms - Not a wiki. Poorly organized and limited to science, math and environmental studies.
- LessonPlan101.com - Lesson Plan Wiki for teachers. Includes a standards-based lesson form and a WYSIWYG editor.
- WikiTeach UK - not-for-profit site for teachers based in the UK. One of the features of this site is a wiki as well as a forum, downloads, blog capability etc. The site is in its early stages as this point but hopefully this will change in the near future when word has spread about the site. Registration is required but is free and will always remain free (valid email address is required).
- Teachers Lounge - award winning webpage for sharing lesspon plans
- Lesson Plans Page - project created by Rob Lucas for sharing lesson plans. Being migrated to a spiffy new version called TeachForward.org
Proposal to Foundation mailing list 
Wikiteach is a proposed encyclopedia of classroom lesson plans and projects. It would be a clearinghouse of teaching ideas, a teachers' bag of tricks, categorized by subject and by grade level. Each subject would be broken down into topics and further into lesson plans. For example, a math teacher who wants to teach fractions would select the subject "Math," then the topic "Fractions," and then a list of lesson plans would appear. She could sort the lesson plans by selecting a grade level -- maybe 4th grade, or maybe remedial college math. Finally, she might use a keyword search to further refine the list.
Wikiteach would be a close cousin to wikibooks, but teachers need lesson plans as much as they need books. Books carry the content --sometimes including lesson plans -- but lesson plans describe how to present the content. They detail the steps a teacher can take to introduce an idea and to lead students to understanding.
Teachers need wikiteach because they are constantly trying out new ideas in the classroom. They spend much time and money improving their lessons. They typically look to books, other teachers and websites for new ideas, but none of these resources is as broad and complete as wikiteach could be. Teachers love to share their ideas, so they would build the database very quickly.
Wikiteach would promote WikiMedia's goal of spreading knowledge, because it would assist teachers as they spread knowledge on a daily basis. This would also increase wiki awarness, because teachers would begin to incorporate wikis into the classroom environment. Thus large numbers of students would be encouraged to use wikis.