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7th Grade Integrated ScienceStandard II, Objective 2

Title: Scale Model of Earth

Description: Students will draw a scale model of Earth.

Materials: 1.5 m x 1.5 m piece of butcher paper (butcher paper is about 1 meter wide. You will need to cut a piece in half and glue to another to get thesedimensions)

1 meter of string, metric rulers, markers, student sheet (see below)

Time Needed: 100 minutes

Background: Earth is a remarkably round, smooth object when viewed fromspace. It is important that students understand that from their view of Earth, it isbumpy but from space, it is quite smooth. A picture of Earth taken from space ishelpful to have to point this out to them. Make sure students understand that thelayers of Earth are NOT visible from space. You might also discuss the reasonsscientists use models (for things to small, too large, too dangerous or thatoccurred in the past) to study and test. Remind them that no one has ever drilledinto Earth past the Core although it has been attempted. Temperatures,pressures and difficulty with the drilling process currently make it very difficult todrill very far into Earth.

Procedures:1. Discuss the introduction on the lab sheet.2. Describe where materials are located.3. Demonstrate how a pencil and string can be used for a compass.

 

4. Emphasis that the layers of Earth are additive. Each level of thickness mustbe measured from the previous one, NOT from the center each time.

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5. If you would like students to do some research, do not give them theinformation on the 3rd table on the student sheet. This information is probablyavailable in their books or if you have computers, this website is a good one:

http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/Earths_layers/Earths_la

yers1.html

6. Students can display their work on the walls of your room and you can quicklydiscuss the merits of each or have student groups report.

Scoring guide:

1. Student works and participates in group............................................42. Group produces reasonably accurate model.....................................43. Model is correctly labeled..................................................................44. Student correctly records data and answers analysis questions......4

5. Student writes thoughtful and thorough conclusion..........................4

Student sheet below:

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7th Grade Integrated Science name____________________  

Title: Scale Model of Earth

Introduction: Earth is not just a ball of rock. It is a complex, layered ball of 

rock. Earthquake waves traveling through Earth do not pass straight through.They bounce off of layers composed of different materials with different densities,states and composition. Scientists measure earthquake waves and have mademodels of what they think is inside Earth. In this activity, you will make a scalemodel of Earth and see the layers and features of the crust in their trueproportions.

Materials:1.5 x 1.5 piece of butcher paper, 1 meter string, metric rulers, markers.

Procedures:

1. To make a scale model, every part of the object being modeled needs to be“shrunk” mathematically. This is done by dividing every part by the samenumber. To make our model, the shrinking factor is 1: 60,000,000. Earth will be60 million times smaller in our model than in real life. In the metric system, our conversion factor will be 60 km on Earth = 1 cm on our model.2. Start by dividing the numbers of the real Earth on the data table below by 60.Put that number in the column for thickness on the model.3. Find the center of your large piece of paper. Put a dot there. Tie a pencil toyour string. Measure the thickness you calculated for the inner core on your paper, starting from the dot. Use the string like a compass and hold it on thecenter and rotate the pencil in a circle the correct size around it.

4. Continue making circles; remember to draw each time from the center but addthe thickness of each layer to the layer before it.5. Add the surface features last.6. When you are done, label each layer by name and write it’s density, phaseand composition on it.7. Answer the analysis questions when you are done.

Data:

Layers of Earth

Earth Layer Real thickness (km) Our model thickness (cm)

Inner core 1255

Outer core 2220

Mantle 2895

Crust 40

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Surface Features

Feature Real Height (or depth)km

Our Scaled Size (cm)

Orbit of Space Shuttle 300

Mt. Everest 8.8Grand Canyon 1.7

Deepest well 8

Deepest ocean depth 11

Layer Density (g/cc) Phase Composition

Inner Core 12.7-13.0 Solid Iron

Outer Core 9.9-12.1 Liquid Iron, nickel

Mantle 3.3-5.5 Solid and semi-solid (“plastic”)

Magnesium, iron,silicate

Crust 2.7-3.0. Solid Silicate,magnesium,aluminum

Analysis questions

1. Which layer of Earth is thickest? Thinnest?

2. If you saw Earth from outer space, how smooth would it appear?

3. How much of Earth would you see looking out a space shuttle window?

4. How do we know Earth has layers?

5. What happens to the density of Earth as you go toward the center?

6. Earth was a molten (liquid) ball of rock when it formed. Why did someelements sink to the center?

7. Why might the outer core be a liquid?

 Conclusion: