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
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?
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