MPS Edtech Site
Great place to start looking up anything!!
Encyclopedia Britannica Online
Britannica has created a friendly search engine that brings level of language to an appropriate level for elementary students.
Great search engine! This site is nicely broken up into categories which make it easy to find things.
What is nice about this site is it is just for kids. Which means it weeds out any inappropriate material making it kid friendly and definitely mom and dad approved!