
A search engine for kids is kigose. It includes some search tips (I suspect that these would be useful for everyone!). In the 'Internet Safety' area there is a section where you can input a site's web address to give you a diagnostic output about the site - very useful for teachers as it is quick and easy.
There are also areas for Art, Literature, Maths, Social Studies, Sports, Technology, and Science. By clicking on these you will find links to appropriate web sites.
In addition there is a 'translation' area where you can have text translated from one language to another as well as a unit conversion area. Very useful site to use in the classroom.