This is an interesting resource for science: 2008/9 Schools Wikipedia Selection : Subject Index
Science is traditional divided in curriculum terms into Chemistry, Physics and Biology. Some of the science articles are long and complicated but "elementary" articles have been included where possible. A good starting point is the "portal" pages for subjects which are listed at the foot of this page together with some general science articles. The Chemistry section is large and includes reference articles on all the elements and common compounds. The Physics section includes Astronomy, the Planets and a lot of technical articles. Biology includes Health and Medicine as well as articles on plants, creatures and lab Biology. There are also several sections on important scientists in the "people" section, divided into "astronomers and physicists" "human scientists" and "chemists".