Lunar and Planetary Institute






Tides:
Content Resources for the Pre-Service Educator

Phil Plait's Bad Astronomy has a section on tides.

Tides and Water Levels: What are Tides?
This tutorial is an overview of the complex systems that govern the movement of tides and water levels. The tutorial is content rich and presented in easy-to-understand language with many illustrative and interactive graphics to visually enhance the text. This page begins with what tides are while other linked pages cover What Causes Tides, Gravity, Inertia, and Bulges, Changing Angles and Tides, The Frequency of Tides, Tidal Variations, Types and Causes of Tidal Cycles, What Else Affects Tides, Monitoring the Tides, How are Tides Measured, and a page of references.
Grade level: High (9-12)
Resource Type: Tutorial

The Causes of Tides
This document explains the predictable and periodic movements of ocean waters that are known as tides and how they are produced by the gravitational forces of the moon and sun. It describes how gravitational attraction and centrifugal force create bulges on either side of the Earth (the high tides), and how two coinciding and simultaneous low tides occur at equal distances around the earth between them. It also explains tidal range and why it varies greatly with geographic location.
Grade level: Intermediate (3-5), Middle (6-8)
Resource Type: Ref. material

NOAA's Tides and Currents
Information on tides, their causes, their variations; data for activities can also be found at this site.