1. Lesson 1.8: Coordinate System
Coordinate System:
*Used to plot points. *Formed by the intersection of a horizontal number line and vertical number line. 8 6 4 2 -2 -4 -6 -8

2. x-axis : the horizontal number line on a coordinate system.
y-axis :the vertical number line on a coordinate system
Origin : the point where the x and y axes intersect (0, 0) y
(0,0) x

3. Quadrants: 4 sections of a coordinate system
Quadrants: 4 sections of a coordinate system. Quadrants are always labeled with Roman Numerals. y I II x
III IV

4. Ordered Pair : a pair of numbers in a specific order used to plot points
x-coordinate : first number in an ordered pair, tells you how to move left/right.
y-coordinate: second number in ordered pair, tells you how to move up/down.
Graph: the point that corresponds to the coordinates.

5. Relationships between quantities
Jimmy and Danny are participating in a free throw shot contest. Jimmy practices his free throws 10 hours each week and Danny practices 2 hours each week. Who do you think will do better in the free throw competition?
Will your heating bill be higher when the temperature outside is 98 or when it is 17?
Jose earned a 98% on his math test. Henry earned a 86% on the same math test. Who is taller, Jose or Henry?

6. Answers:
Jimmy
2) 17
3) Can’t tell
The more you practice the more free throws you make. Positive relationship.
The lower the temp., the higher your bill – Negative Relationship
Your math test grade has nothing to do with your height – NO Relationship

7. Positive Relationship: As one quantity (amount) increases, the other also increases
Ex. Time you study and score on test
Negative Relationship: As one quantity (amount) increases the other decreases. Ex. Temperature outside and heating bill
NO relationship: One quantity (amount) has no effect on the other.
Ex. Height and yearly income
Scatter Plot: A way of displaying data using a coordinate system, shows if there is a relationship between quantities. Typically only use first quadrant of coordinate system.

8. Grade compared to study time
Line of best fit
100 80
Overall Grade 60 40 20
# of Homeworks completed

9. Speed vs. Travel time to Harrisburg
Time to get to Harrisburg in minutes
160
140
120
100 80 60 40 20
Speed - mph

10. Scatter Plot – Up to right, positive relationship
- Down to right, negative relationship
- No pattern (points scattered all over
coordinate system – no relationship
Scatter plots MUST have:
Title
Labels on axes
Uniform Scale

11. Homework: p. 207 #12-26 evens
#27-32 all, #35-38 all