1. What Is a Wave? Most waves form when winds blowing across the water’s surface transmit their energy to the water. - Wave Action

2. Water Motion Activity Click the Active Art button to open a browser window and access Active Art about water motion. - Wave Action

3. How Waves Change Near Shore Near shore, wave height increases and wavelength decreases. - Wave Action

4. How Waves Change Near Shore A tsunami is usually caused by an earthquake beneath the ocean floor. - Wave Action

5. How Waves Affect the Shore As waves come into shore, water washes up the beach at an angle, carrying sand grains. The water and sand then run straight back down the beach. - Wave Action

6. What You Know What You Learned Using Prior Knowledge Before you read, look at the section headings and visuals to see what this section is about. Then write what you know about waves in a graphic organizer like the one below. As you read, write what you learn. 1.There are waves in the ocean. 2.Wind causes waves. 1.Waves move energy to the shore. 2.Earthquakes cause tsunamis. - Wave Action

7. Wave Characteristics Click the Video button to watch a movie about wave characteristics. - Wave Action

8. End of Section: Wave Action

9. What Causes Tides? Tides are caused by the interaction of Earth, the moon, and the sun. - Tides

10. What Causes Tides? Spring tides and neap tides are caused by the positions of Earth, the sun, and the moon. - Tides

11. Plotting Tides This table lists the highest high tides and the lowest low tides for one week at the mouth of the Savannah River, where it meets the Atlantic Ocean in Georgia. - Tides

12. Plotting Tides Graphing: Use the data in the table to make a graph. On the horizontal axis, mark the days. On the vertical axis, mark tide heights ranging from 3.0 to –1.0 meters. (Hint: Mark the negative numbers below the horizontal axis.) Check students’ progress as they make their graphs. The number –1 should occur at the base of the y-axis. - Tides

13. Plotting Tides Graphing: Plot the tide heights for each day on the graph. Connect the high-tide points with one line and the low-tide points with another line. Make certain that students connect the correct points with lines. - Tides

14. Plotting Tides Interpreting Data: How do the high and low tides change during the week? During the first six days, the high-tide value increases steadily while the low-tide value decreases. On day 7, the trends reverse. - Tides

15. Plotting Tides Inferring: What type of tide might be occurring on day 6? Explain. Spring tide might be occurring on day 6, when there is the greatest difference between high and low tides. - Tides

16. Previewing Visuals Before you read, preview Figure 11. Then write two questions you have about the diagram in a graphic organizer like the one below. As you read, answer your questions. Q. When do spring tides occur? A. During the full and new moon phases Q. What is a neap tide? A. A smaller tide that happens at the first- and third-quarter moons Spring and Neap Tides - Tides

17. More on Tides Click the PHSchool.com button for an activity about tides. - Tides