ive Teaching Press Inc., 2009, ISBN 1591987083
After providing basic information about the Moon, the author discusses eclipses, gravity, and tides. Appropriate for children ages 9–12.
Exploring Our Solar System
Sally Ride and Tam O'Shaughnessy, Crown Books for Young Readers, 2003, ISBN 0375812040
This well-illustrated book takes children ages 9–12 on a tour of the planets (and our Sun!) in our solar system. In addition to clear explanations of lunar phases and Earth's seasons and tides, this book includes a timeline of major events in the history of our planet.
For the children:
For the facilitator:
- Review the background information.
- Print images of high and low tide. You may choose to present images of the Bay of Fundy, or you may wish to provide your own photographs of a local coastline or from a beach vacation. Be sure to photograph high and low tide from the same location for easier comparison.
- Display several books and videos about oceans, seashore animals, and the Moon and tides in a place where the children can page through them before and after the activity. Encourage the children to check them out at the end of the program for further investigation.
Facilitator's Note: This activity builds upon the fact that the Moon has gravity, but the children may have false ideas about the concept of gravity. You may wish to first undertake the activity Heavyweight Champion: Jupiter, where children ages 9–13 can discover whether other planets and the Moon have gravity and what causes this natural force.Advanced learners may wish to explore the complex relationship between the Moon (and its phase), the Sun, and Earth. Older children may create their own tide wheels.
Part A: The Moon’s Gravity Creates Ocean Tides
1. Ask the children to consider the reason behind the difference between images of high and low tide. Show the images to the children and have them describe the differences between them. Guide their discussions toward identifying them as tides, and finally, toward relating the Moon as the main cause of that pattern.
- What do you notice about these pictures? There are four images of the Bay of Fundy (on the east coast of Canada) Two are satellite images, taken several months apart. Two were taken on the ground at different times on the same day. Each pair shows the water level at a different height, which in one image, left the boats grounded!
- Have you ever been to the coast and seen the ocean? Have you ever explored tide pools?
- What happens to the level of the ocean water over the course of a day? They rise and fall. In some places, this occurs once a day. In others, in occurs twice a day.
- What do we call this daily rise and fall of ocean waters along coastlines? Tides.
- What causes tides? The children may know that the Moon’s gravitational pull causes tides.
Add that the Sun's gravitational pull also helps create tides. However, the Moon's gravitational pull gives the tides their height and regular, daily pattern. An area's geographic location and the shape of the sea floor also affect the tide.
Facilitator's Note: There is a tricky distinction between waves and tides. The waves we like to watch breaking along the beach are caused by wind and are independent of tides. Tides cause the water level to be really high up on the beach, or really far out (often leaving clams and other sea life exposed), and everything in between.
A tidal wave, or tsunami, is caused by a sudden disturbance — such as an earthquake — and is unrelated to tides. If the conversation turns to tidal waves, gently clarify this distinction.
2. Explain that six children will model how the Moon’s gravitational pull creates tides. Because the Moon and Earth are in motion together as they orbit the Sun, this model will be similar to a dance. Have one child put on the T-shirt and represent the solid Earth. Have four other children wear blue T-shirts and stand in a circle around the "Earth": one behind, two on each side, and one directly in front of "Earth." These children represent Earth's oceans. The oceans are linked by four scarves or str