Bay Link - Your Backyard Classrooms

A Lesson Plan from the Virginia State Parks'
Your Backyard Classrooms

Objectives:
Students will investigate tidal patterns by:

determining the times and water heights of low and high tides at a designated reference station for a particular day using a tide chart;
calculating the tidal defferences between the reference station and any other location;
comparing the effects of the moon phases on tidal height.

Science:

Grade Six: 6.1, 6.2, 6.10
Earth Science: ES.1, ES.2, ES.4, ES.11
Physical Science: PS.1, PS.10

Mathematics:

Grade Seven: 7.21, 7.23
Grade Eight: 8.18

Students will learn to read a tide chart, determine the times of the high and low tides for a particular day for a standard reference point, as well as the tidal height relative to mean low water. Using this information, they will learn how to correct for differences in tidal times and heights for any other location on the same day.

Background:
A tide is a special type of wave which is perceived as the vertical movement of ocean waters. Tides are caused by the gravitational pull of the moon and sun. Although the moon is very small compared to the sun, it is much closer to the earth.

As a result, its tidal influence is more than twice that of the sun. These gravitational forces "pile up" water into bulges which move as long waves around the earth, creating in the Chesapeake Bay, and in many other locations, two high and two low tides every 24 hours and 40 minutes. Such tides are calied semi-diurnal tides. Other parts of the earth, such as the Gulf of Mexico, experience diurnal tides--one high and one low every day.