PBS
Pbs Learning Media: More on Galileo's Big Mistake
Even great scientists make mistakes! This illustrated essay from the NOVA Web site looks at Galileo's theory of the tides, which, while well thought out, was wrong.
CK-12 Foundation
Ck 12: Earth Science: Tides Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide summarizes key points about the different types of tides and the Moon's effect on Earth's tides. Includes a few questions to check for understanding.