The following sites are specific to particular content areas. Another recommended source is museum websites. Famous museums like the Smithsonian has free lesson plans for teachers.
The Internet offers a wide range of information and perspectives, much of it incorrect-- or, at the very least, incomplete or biased. So consider these criteria for evaluating websites: Authority, Content, Currency, and Reliability. Ask these questions …
Questions of Authority
Questions of Content
Questions of Currency
Questions of Reliability