In this investigation your students toss an inflatable globe to determine how much of the Earth’s surface is covered by ocean. They will estimate, make predictions, do 2 trials (tests) and make a pie chart of their results.

Before beginning the investigation, ask your students what they know about Earth’s oceans. Can they find them on the globe? Do they know the names of any of them?

Students can work alone, in teams or in groups. Younger students could work as a whole class with you tossing the globe, a student catching it and you recording their results on the board. Older students can work on their own, complete the pie chart and answer the questions on the student data sheet. They can make their estimates as fractions or in percentages. You could have the students complete their trials and then compile a table and pie chart of class results.

About 70% of the Earth’s surface is covered by ocean water. That also means that about 70% of the Earth’s crust, land, is underwater.

After completing the investigation have students share what more they would like to find out about ocean water. One question that you might want to explore with the globe is: “Does the Earth have five oceans or just one?” Students can put a finger on the ocean and try to follow it all around the globe. Ask them to explain why they think one ocean or five oceans is the best choice. Take a vote. If the one ocean choice wins, have a contest to name Earth’s one ocean.

- inflatable Earth globe available here. 1 per team/group
- student data sheet. 1 per student

First Trial:

- Make an estimate. Look at the globe. How much of it is covered by ocean water? Record your estimate as a fraction or percentage on your data sheet.
- Make a prediction. How many times do you think your thumbs will touch the ocean when you toss and catch the globe 10 times. Record your prediction on your data sheet.
- Toss the globe into the air and catch it with both hands.
- Look at your hands. Are either one of your thumbs touching a part of the ocean? If so, put a mark in the ocean column on the data sheet. If not, put a mark in the land column.
- Keep tossing, catching and recording your results for a total of 10 tosses.

Second Trial:

- Using your first trial results, make another estimate about how much of the Earth’s surface is covered by water. Record your estimate on our data sheet.
- Now make another prediction about how many times you think your thumbs will touch the ocean when you toss and catch the globe 10 times. Record your prediction on your data sheet.
- Toss the globe into the air and catch it with both hands.
- Look at your hands. Are either one of your thumbs touching a part of the ocean? If so, put a mark in the ocean column on the data sheet. If not, put a mark in the land column.
- Keep tossing, catching and recording your results for a total of 10 tosses.

Make a Pie Chart:

- Total the results of your trials and record the totals on your data sheet.
- Each section of the pie chart represents one catch. Color the land catches brown and the ocean catches blue.
- Now make a new estimate of how much of the Earth’s surface is covered by ocean water.

Think about what you did and why:

- Answer the questions on the student data sheet.

Earth's Oceans See if you can find the answer to the question “How much of Earth’s surface is covered by ocean water?” and questions you have about Earth’s ocean water.