**Scale Models in Science**

Scientists often build and study models to better understand things that cannot be studied directly due to size (too big or too small), speed (too slow or too fast), and safety. Models help scientists explain their findings and even help scientists to develop new questions. Therefore, it is important that scientists build

**models that fairly represent the actual object under study.**

*scale**What is a scale model?*A

**is an enlarged or reduced representation of an object that has the exact same proportions as the actual object. Maps and floor plans are great examples of scaled models (drawings), as is the typical plant and animal cell illustrations in textbooks and online.**

__scale____model__Below (left) is a scale model of our Solar System. Check out the video on the right to observe a model of our Solar System that is

**scaled.**

*NOT***Converting Units**

One of the most important skills scientists need to build a scale model is the ability to convert units. In order to convert units, we must first find the scale factor/unit rate.

**is simply the relationship between two different units (scales). All you need to find the scale factor/unit rate is a scale. For example, 1 meter = 100 centimeters. The scale factor would be 1/100 m/cm, OR, 0.01 m/cm.**

__Scale factor/Unit rate__We will use the following method to convert units:

1. Find the

**(unit rate).**

__scale factor__2. Multiply the scale factor (unit rate) with the unit you want to convert.

3. Cancel units. There should only be one remaining unit.

**if you set it up right, the unit you want to convert TO should be left**

**Example: Converting MYA to centimeters**

The Earth's magnetic field was formed 3,500 MYA.

*How would you convert this date to centimeters so that you can mark this event on a geologic time scale if the scale is 1 cm = 10 MYA?*

Let's walk through the 3 steps to find our answer:

1. Find the scale factor (unit rate).

1 cm/10 MYA =

**0.1 cm/MYA**

2. Multiply the scale factor (unit rate) with the unit you want to convert. 0.1 cm/MYA x 3,500 MYA =

**350 cm**

3. Cancel units. There should only be one remaining unit.

In step 2, MYA was cancelled out because MYA/MYA = 1

**Scale Model of Earth's Interior**

**Background**

The Earth's interior is made up of 4 layers. The outermost layer is called the

**, just like the outermost layer of bread. The crust is made up of solid, lighter rocks that make up the continents and ocean floor. The**

__crust__**is the layer between the crust and the Outer core. The mantle is made up of heavier, molten rock (aka magma) that is plastic (flows and moves), just like the lava that erupts from a volcano. Beneath the Mantle is the**

__mantle__**, which is made of liquid iron and nickel. At the very center of the Earth is the**

__outer core__**, which is made up of solid iron. As you move closer to the center of the Earth, temperature and pressure increase.**

__inner core__**Holiday Homework Overview**

Over the Mid-Winter Recess, you will be designing and building a scale model of Earth's Interior. In order to do so, you will need to convert units from kilometers to centimeters. This is because the Earth's layers are measured in kilometers (see above). The unit conversions for each layer is the design/planning portion of the project. Then you will use the converted measurements to start building your actual model. With that said, complete the practice questions below to help you prepare to design and build a scale model!

**Assignment**

Copy the questions and answer them in complete sentences. Make sure to title the assignment "Scale Models in Science and Converting Units".

Due: Friday, February 14, 2014

1. Provide 3 reasons why the Solar System in the Jimmy Dean commercial (above) is not a scale model.

2. The first humans are believed to have reached North America 0.13 MYA. Convert this date to centimeters. Scale: 1 cm = 10 MYA

3. The Indian continent collided into the Asian continent approximately 50 MYA, creating the Himalayas. Convert this date to meters. Scale: 1 meter = 50 MYA

4. Convert 15.2 feet to inches. Scale: 12 inches = 1 ft

5. Convert 2500 milliliters to liters. Scale: 1 L = 1000 mL

6. How might you start designing your scale model of Earth's layers given the thickness of each layer (in picture above) if the scale were 1 cm = 6372.5 km? Make your best guess using the same method for questions 2-5.

7. Complete the form below.