This is a great search engine for children. You can search by word, first letter of the subject, or use their handy subject areas. All sites are rated by age range and are child-safe. You can search either by their grouped subjects, like School Bell, Around the World, or Science and Other Oddities or by your own keyword. It also offers a site of the week, and much more.
All sites are child appropriate.
Although there are many sites here are for educators, these sites are primarily aimed at children and teens. The searchable database boasts 50,000 child-appropriate sites, as well as a feature list of subjects and regularly changing sites. Fast and fresh.