Tides and the Gravitational Pull of the Moon
Driftwood Journey Curriculum
Objective: Students will learn that different things in their environment interact even when they appear to be unrelated.
- Students will understand there are low tides and high tides.
- Students will understand the role of the moons gravitational pull on tides.
- Students will understand the moon and sun both play a role in creating tides.
- Paper clips
- Calendar that has moons phases
- Tide table
People to be included: Elders
Gear up: Tell students that even though the moon and sun are in outer space and the ocean is on Earth, there is a relationship among them. One thing often affects another, even if we cant see it with our own eyes right away. Tell them the moon moves around the Earth every 24 hours and creates a bulge in the water as it moves around. Wherever the moon is, there is a high tide. At the same time, on the opposite side of the Earth there is another bulge and a high tide. Thats why we have two high tides, not just one. When the sun, Earth and moon are lined up in a straight line (new moon and full moon) the gravitational pull is the strongest and thats when the tides are highest.
Explore: Activity #1: Tell students that tides are caused by the gravitational pull of the moon. Tell them that gravitational pull works like a magnet. Ask if they have seen refrigerator magnets and if they know how they work.
Give each student a small magnet and 5 or 6 paper clips. Tell them the magnet is the moon and the paperclips are the water on Earth. Ask them to hold the magnets about 5 inches from the paperclips, then start to move the magnet slowly in a circular motion around the paper clips. If none of the paper clips moves at all, tell them to move the magnet a little closer and continue making slow circles until one or more of the paper clips begins moving along with the magnet. Tell them to try to keep the paper clips moving around without letting them get attached to the magnet.
Generalize: Ask them if they can see more beach at high tide or at low tide? (Low tide.) Ask them when is the best time to find things on the beach, low tide or high tide? (Low) Ask them if they think there is a high and low tide every day or only during the full moon? (Daily.) Ask them if they know how many low tides and high tides there are every day? (Two of each in a 24-hour period.)
Explore: Activity #2: Pass out a calendar page that has the cycles of the moon on it. Pass out a tide table for the same month and explain how to read it. Ask students to write the high tides and low tides for each day on the calendar. When everyone is done, ask the students to look at the page to see which two days have the highest tides. Ask them to confirm those happen on the days there is a new moon and the day there is a full moon.
Generalize: Would they be able to tell which days have the highest tides in a different month if the only information they had were the phases of the moon, but no tide table for that month?
Tell them the oceans and the weather are often stronger on days when the highest and lowest tides occur. Their ancestors knew that and so they planned their trips accordingly. They often chose not to travel on those days, or, if they had to, they knew they had to be more careful because the weather would be rough.
1. A Driftwood Story
2. Properties of Wood
3. Cultural Uses of Wood Past and Present
4. Tides Gravitational Pull of the Moon
5. Wind, Tides and Currents
6. Earthquakes and Tsunamis
7. Afognak and the 1964 Tsunami
(Camp version, classroom version)
8. Celebration of Trees
Driftwood Stories and Poems
9. Celebrating Alutiiq Customs and Traditions
Appendix: Resources Used