You will be exploring the upper crust of the Earth, which is the layer extending 10 to 40 km beneath the surface. The surface temperature averages 15 degrees Celsius and increases 25 degrees Celsius with each kilometer of depth. Create and use a temperature model to help determine the range of temperatures you could expect to encounter while traveling within the boundaries of the upper crust. 2. Define the variables you will use in your equation. (1 point)
Let one variable be the distance away from the surface and the other variable be the temperature.

The y-intercept is the starting position at Earth's surface. The coordinates of the y-intercept are (0, temperature at Earth's surface).
3. What is the b-value of the y-intercept for your equation? (1 point)

The slope is the rate of change for temperature.
If the temperature increases (gets hotter) as the distance from the surface increases, then the slope is positive.
If the temperature decreases (gets colder) as the distance from the surface increases, then the slope is negative.
4. What is the slope of your equation? (1 point)

5. Write an equation that models the relationship between your variables. (1 point)

Interpreting the Equation
6. Identify and explain what each term represents in the temperature model.
a) The slope (1 point)

b) The y-intercept (1 point)

Graph the line
7. Identify three points on your line. (1 point)

8. Using the coordinates from question 7, calculate the slope of your line. Does it match the slope from your model? (2 points)

Graph the Equation
9. On the graph below, plot the points and sketch your line. (4 points: 1 for each graphed point, 1 for the line)

Find the Temperature Range
10. Complete the sentence for your layer. (1 point)
The troposphere is the region that starts at Earth's surface and ends between km and km above Earth.

The upper crust is the region that starts at Earth's surface and ends between km and km below Earth's surface.
Use the temperature equation to find the temperature range for your layer.
11. What is the temperature at the end of your layer that is farthest from the surface? (1 point)

12. For the layer you selected, the temperature ranges from the temperature at Earth's surface, , to . (1 point)