A fun site that allows you to test your math and science knowledge, the Explore Your Knowledge site from NCES is a lot of fun. The tests are divided between fourth and eighth grade and the user can choose from either math or science. Also, while there are nearly 120 questions, the user can decide how many to tackle at once -- from 5 to 20. After answering the multiple choice questions, the computer not only scores the test, but gives the correct answer for those that you answered incorrectly. Overall, a fun little module for students to use.