1. Slope

2. Ski Bird is going to try to help you remember how slope applies to straight lines. change in y over change in x. Slope is defined as… rise run

3. What is rise? The rise is the vertical change that occurs on the y-axis. If it goes up, it is positive. If it goes down, it is negative.

4. What is run? The run is horizontal change that occurs on the x-axis. It runs from left to right. If it goes left, it is negative. If it goes right, it is positive.

5. Positive Slope Lines that have positive slope, slant "up hill" (as viewed from left to right). Ski Bird has to work hard to make it up the hill. He needs to exert more positive (+) energy to get up the hill.

6. Negative Slope Lines that have negative slope, slant “down hill”(as viewed from left to right). Ski Bird enjoys the ride down the hill. He needs to decrease (-) energy to try to slow down.

7. Zero Slope Lines that are horizontal have zero slope. Ski Bird is cross-country skiing on level ground. He is not working hard to get up a hill, nor is he trying to slow down. His energy level (and his enjoyment level) is at zero.

8. No slope Vertical lines have no slope, or undefined slope. Ski Bird cannot ski vertically. Sheer doom awaits Ski Bird at the bottom of a vertical hill.

9. Slope can be expressed different ways: A line has a positive slope if it is going uphill from left to right. A line has a negative slope if it is going downhill from left to right.

10. When given the graph, it is easier to apply “rise over run”. 1) Determine the slope of the line.

11. Start with the lower point and count how much you rise and run to get to the other point! Determine the slope of the line. 6 3 run 3 6 == rise Notice the slope is positive AND the line increases!