GRADE: Fifth

CONTENT STANDARD: Earth and Space Science

CONTENT TOPIC: Oceanography

CONCEPT: The topography of the ocean floor is in constant change.

CONTENT OBJECTIVE: 5M1.00 To understand the structure and constant changing of the ocean floor

INSTRUCTIONAL OBJECTIVES: The learner will:

1.01 discuss the process of sedimentation.
1.02 discuss the continental drift theory.
1.03 locate major structures on the ocean floor.
1.04 identify life forms at each level of the ocean.

I. Sedimentation
II. Plates of the earth's crust
A. Some plates have continents
B. Some plates contain parts of the ocean floor
C. Each plate moves slowly on its own
III. Major ocean floor features
A. Mid-Atlantic Ridge
B. Fault lines
C. Mountains

TN COMPONENT OF SCIENCE: Unifying Concepts of Science

TN GOAL:

To enable students to acquire scientific knowledge by applying concepts, theories, principles and laws from life/environmental, physical, and earth/space science.

2.5 CHANGE - Interactions within and among systems may result in changes in the properties, position, movement, form, or function of systems.

2.5a Everything is constantly changing; rates of change vary over a wide scale with a great variety in patterns of change.

BENCHMARK: Things change in consistent and repetitive ways. Some features may stay the same while others change.

2.5b Cycles of change can be extended in scales of time, space, and material.

BENCHMARK: Changes can occur slowly or quickly within any system.

BENCHMARK:Materials may combine to form new materials. The properties of the new materials may be unlike the original materials.

TIME REQUIRED:

Three instructional periods

Paper cups (one per student), salt for salt/water solution, chart with dissolved minerals list, poster of ocean floor, duplicating sheet with drawing of each continent, large world map, map depicting ocean years ago, poster depicting levels of ocean life. Clay, sand, gravel, jars - enough for five groups, diagram of topography of the ocean floor

(Have a diagram showing composition of ocean water which indicates that it contains 965 grams of water to 35 grams of salt. Mix a solution of this and have students taste from paper cups.) Do you think it tastes like ocean water? (response) Do you taste salt? (response) Ocean water is mostly pure water, but there are many different substances dissolved in the water. Today we will learn about some of the substances that make up ocean water and all the changes that occur over time.

(Have a chart or transparency with 3 categories--consistent changes, inconsistent changes, and repetitive changes) Today as we discuss the ocean, raise your hand and tell me every time you notice something about the ocean that is a kind of change. We will write it on the chart and label it "S" if it is a slow change and "Q"; if it is a quick change. (Add to the chart throughout the lesson.) Let's discuss the experiences of swallowing ocean water. How does the water taste? (response) What happens if you drink too much? (Feel bad) Can you see to swim in the ocean near the shore? (Sometimes yes - sometimes no, because of materials in the ocean.)

Here is a chart with dissolved minerals listed. It shows the composition of ocean water. How did this get in the ocean? (response) (Yes, rivers carry 8 million tons of salt and sediment to the sea each year. Some sediments are deposited near the shore. Some are picked up by wind and blown out over the sea where it eventually falls to the sea and settles. Scientists have drilled the ocean bottoms and found brown or red clay covering a large part of the floor. What examples of change have you seen? (Add to chart.)

(Divide students into groups of five or six. Hand out jars, some gravel, sand, and clay to each group. Have them fill the jar 1/2 full of these substances. Add water until the jar is almost full. Screw lid on tight and shake vigorously for one minute. Put it down and observe. Have groups report on their observations. If they do not use the word "settle", prompt them by suggesting what settles first, second, last. They may need to shake again and make new predictions about what will happen. Students should conclude that large sediment settles to the bottom first, and light, finer sediment settles next. Relate this conclusion back to substances settling in the ocean. Also, more than half of the ocean floor is formed from tiny living things that die and become part of the floor which forms ooze.) What examples of change have you seen? (Add to chart.)

(Research minerals and substances in the ocean and do a bar graph by percentages.)

Have poster or bulletin board depicting ocean bottom. Have drawing of each continent on a duplicate sheet. Let them label each one and cut out each continent.)

The continental shelf starts where the part of land we live on ends. It is part of the continent, but covered with water. It is the shallowest part of the ocean. At the end of the shelf, the continent plunges downward sharply. This is called the continental slope. The ocean floor begin where the slope ends and covers most of the ocean bottom. Part of the floor is flat. It is called the abyssal plain.

Part of the floor is mountain ranges. A mid-ocean ridge runs through every ocean on earth. (Come back to this in great detail and see how they are formed.)

(Use continents the students labeled and cut out.) Do they fit together and match? (No, they won't fit together or match) What is missing? (Water) Three-fourths of the earth is covered with water. (Have a large world map.) The earth is like an apple with three parts. (Review composition of core, mantle and crust.) Continents and oceans sit on crustal plates, like pieces of a giant puzzle. These plates move slowly on top of the mantle, approximately three centimeters (one inch) per year. As they move, some rub and scrape against each other. How and why? (response) Hot rock rises from the mantle through the crust. This rock cools and hardens on the edge of the plates. As new crust is added, plates on either side of the mid-ocean ridge move slowly away at a pace of about three centimeters one inch) per year. (Show a map depicting the oceans years ago and now, to show the continental drift theory.) The Pacific Ocean is getting smaller. There is also a large crack in the center of the mid-ocean ridge which is 8-30 miles wide and one mile deep. (Relate earthquakes and volcanoes to this and earthquakes "Ring of Fire";. Include in this discussion the formation of the ocean floor.)

Sediments are deposited near the shore on continental shelf and abyssal plains. These sediments slide over continental shelf and slope to form submarine canyons. This movement cuts a groove in the shelf. To determine the exact composition of the floor, scientists use sonic boom. This tells depth of trenches, and height of ridges.

Trenches, some of the deepest places in ocean are formed as the ocean floor moves downward under the land that borders the ocean (part of continental drift). Deep trenches are where crustal plates are sinking.

Ridges are underwater mountain ranges that were formed when molten rock pushed up under the mid-ocean ridge, cooled and hardened forming more mountains. Some are so high that they stick out of the water. An example is the Azores.

Seamounts are some underwater mountains that are formed by volcanoes, some have flat tops. The Hawaiian Islands are an example of seamounts.

The abyssal plain is at the base of the continental slope. The floor becomes broad and flat, like a plain. The abyssal plain make up almost half the ocean floor. The plain has trenches. What examples of change have you seen? (Add to chart.)

(Students may design ocean floor, papier-mâché' models. Do in groups or individually. Be sure they include ridges, seamounts, trenches, plains and canyons. Also, they can make volcanoes to show how they form from under the ocean floor. Have a work sheet for students to label parts of the ocean bottom.)

In this lesson, we learned about the structure of the ocean floor and how it is always changing. What is sedimentation and how does it affect the ocean water (Particles of soil carried to the ocean by rivers change the taste and content of the water.) Tell your neighbor one thing you've learned today about the ocean. (pause, then summarize) We have seen that many materials in the ocean formed from different materials. Using the charts we have made for reference, make a chart with these categories. New materials, old material it formed from, where material came from and how it got there. In your groups discuss your ideas, record them on a chart and be ready to share your ideas with class. (Allow time to complete and share charts.)

Now write a paragraph about ocean changes. Tell whether they are consistent or inconsistent and if they are repetitive. Include in your paragraph features that remain the same.

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