Mini Lesson Question
Question #2: Describe Graphs
Match a Description with a Graph
A graph can be used to model a situation. You can use what you know about slope and -intercept to connect the graphs to real situations.
Match each description with one of the graphs above:
1. Elena begins at home and runs away from her home at a constant rate.
Elena starts at home, so the graph must start at the origin. She moves away from home at a constant speed, so the graph must be a line that increases to the right. Graph B matches the description.
2. Clare begins her walk at school and walks home at a constant rate.
Clare starts at school, so the -intercept is a point on the -axis that shows the distance her home is from the school. She moves closer to home at a constant speed, so the graph must be a line that decreases to the right. Graph C matches the description.
3. Lin begins at home and runs away from home, and then walks for a while.
Lin starts at home, so the graph must start at the origin. She starts running and then walks, so the graph is a line with a slope that starts off steep and then continues with a less steep slope. Graph A matches the description.
Try it
Try It: Match a Description with a Graph
Describe the graph. You can use the wording from the previous problem as a guide.
Here is how to describe the graph:
The graph starts at the origin, so the walker starts at home. The line is increasing, so the walker is moving at a constant speed away from home. Then the line decreases at a constant rate, so the walker is moving at a constant rate toward home.
Here is a possible description:
Lin begins at home and walks away from home for a while, and then she walks back home.
Check Your Understanding
Which statement best describes the situation shown in the graph?
Multiple Choice:
Max begins his walk at the library and walks away from home at a constant rate.
Max begins his walk at the library and walks home at a constant rate.
Max begins his walk at the library, walks home at a constant rate, and then walks away from home at a constant rate.
Max begins at home and walks away from home for a while, then walks back home.
The -intercepts shows that he starts at a distance from home and moves at a constant rate to home. Then he walks away from home.
Video: Slope and Intercept in Tables
Watch the following video to find the meaning of slope and intercepts in context.
Khan Academy: Slope and Intercept in Tables