Check out the American Association of School Librarians (AASL) web site for the yearly list of the top 25 sites for teaching and learning. The list is organized into useful categories and is full of great sites. A good strategy is to spend some time going through the list and add a bookmark for the ones that you are interested in using. Also take a look at lists from previous years. Time magazine also has a list of the best sites each year that includes an education category. Jot down notes as you go through the lists so that you will remember all of your ideas for using the sites later.
There is a myriad of websites available online which can give you all sorts of learning tools. My personal favorite is Atomic Learning.com, which teaches you how to do integrative technology. For worksheets, and other activities there are also plenty: Apples4theteacher.com; superteacherworksheets.com; tlsbooks.com, and there also is TeacherTube.com. TeacherTube is very similar to YouTube, but teachers basically are the ones who upload their material (including yours truly).
For powerpoint presentations you should go to slideshare.com, or box.net.
All those sites are free of charge. In any case, go to google and type in "free teaching sites" and you will find way more than you will ever think. So, try it out and let us know what u think.
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