Two-Variable Data• On the coordinate plane, plot points with

given coordinates, and determine the coordinates of plotted points.

• Represent a two-variable data set with a scatter plot

• Given a pair of calculator lists, plot points whose coordinates are in those lists.

• Interpret scatter plots• Learn and use vocabulary related to

coordinates and graphs

One Variable Data

Two- Variable Data

Scatter plots

x

y

Two- Variable Data

Abscissa

Ordinate

(x,y) is called an ordered pair

Origin

Coordinate Plane

Two- Variable Data

(-1,2)

• Place the Four Quadrant Coordinate in your Communicator®

• Look at the page of vocabulary and then label the various parts of the coordinate grid

(-2, -4)(3,5)

abscissacoordinate planeordered pair (x,y)

ordinateorigin

Quadrant IIQuadrant IQuadrant IIIQuadrant IV

x-axisy-axis

Two-variable data points are described by pairs of numbers.

They can be represented in a scatter plot, in which each point has one of those pairs as its coordinates on the coordinate axis.

Let It Roll

Where: Page 70What You’ll need

Centimeter rulerCentimeter tapeA Ramp (Book)An Object to Roll (A pencil)Masking TapeGraph Paper

QuestionHow far will an object roll?How does the release height of a ramp

affect this distance?Let’s collect some data to answer these

questions.First data will be the height of the rampSecond data will the distance from the book

that the object stops

Set up your experiment as shown. Mark the point on the ramp from which you will release the rolling object. Make sure that you have plenty of room in front of your ramp for the object to roll freely. Record the release height of the object in a table like this one.

Release height (cm) Roll distance (cm)

Release the object and let it roll to a stop. Measure the distance the object traveled

from the base of the ramp to its stopping point.

Record this in your table.

Repeat the experiment at least five times, using a different release height each time. Record the data in your table.

Place the grid paper in the Communicator®.

Create a set of axes on your graph paper. Label the axes as shown.

Height (cm)

Dis

tance

rolle

d (

cm)

Scale the x-axis appropriately to fit all your height values. For example, if your largest height was 8.5 cm, you might make each grid unit represent 0.5 cm. Scale the y-axis to fit all your roll-distance values. For example, if your longest roll length was 80 cm. you might use 10 cm for each vertical grid unit. Height (cm)D

ista

nce

rolle

d (

cm)

Plot each piece of two-variable data from your table.

Think of each row in your table as an ordered pair.

Locate each point by first moving along the horizontal axis to the release-height measurement.

Then move up vertically to the corresponding roll distance.

Mark this point with a small dot.

Describe any patterns you see in your graph.

Is there a relationship between the two variables?

Enter the information from your table into two calculator lists. Make a scatter plot. The calculator screen should look like the graph you drew by hand. (See Calculator Note 1F)

Turn to page 72 Read the example on this page.

Assigning HomeworkType Questions

Essential 1, 2, 4, 7, 10

Performance Assessment

5, 7

Portfolio 8

Journal 6

Group 8, 10

Review 11, 12

LinkingTurn to Calculator Note 0F on page 4 of the

Calculator NotesFollow Directions for obtaining a Points

programFollow Directions for sending a Points

program

Use the Calculator for PracticeRun the Points

program. Press PRGM and select

Points.Press Enter when you

see prgm POINTS on the homescreen.

Further directions appear on page 17 in the Calculator Notes (Note 1G)