Wikimedia
Wikipedia: Rational Numbers
Learn the definition of rational numbers. You can also look at some examples and properties, plus learn about Egyptian fractions. Links are provided for additional information.
Richland Community College
Richland Community College: Math 116 Lecture Notes
This site from the Richland Community College provides the detailed lecture notes to a college algebra course, complete with equations and definitions. Content ranges from "functions and their graphs" to "conics and parametric equations."
Khan Academy
Khan Academy: Approximating Square Roots
Practice finding the approximate value of square roots by thinking about perfect squares. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.