Lesson One: What is slope?
Introduction to Graphing and Graphical Analysis.
Grade Level: 10
Subject: Coordinated Science
Learner Outcomes:
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Students will use the Internet as a resource.
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Students will manually create a graph.
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Students will learn to use "Graphical Analysis" by creating
a graph.
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Students will demonstrate understanding of the concepts:
slope, independent variable and dependent variable.
Duration of the lesson: Two 45minute
sessions
Materials: Centimeter ruler, miscellaneous
cylinders (coins to coffee cans), scissors, string, centimeter graph paper,
pencil, and copy of the worksheet provided for the Internet site.
Technology Tools/courseware:
PC with Internet Connections, Browser of Choice, Vernier’s
Graphical Analysis for Windows
Teacher notes:
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Students should be familiar with the use of a computer and
how to explore the Internet.
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The worksheet for Lesson A should be printed out for each
student or group.
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The worksheet for Lesson B should be printed out for each
student or group.
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Teacher should collect and gather all materials for lesson
B prior to lesson, remember there should be 5 different sized items, e.g.
coins, juice cans, soup cans, petri dishes (anything that is a cylinder).
Procedures:
Students will complete the following lessons A and B.
It is important to complete them in order.
Lesson A:
Teacher will divide the class into groups according
to the number of computers available and complete the following discovery
activity.
Students will go to the following site to manipulate the
variables on line and to discover slope:
http://id.mind.net/~zona/mmts/functionInstitute/linearFunctions/lpsf.html
Print the following student handout and give a
copy to each student or group.
_____CUT HERE__________________________________________________________________
Name
Date
Period
Group members
1. Click on the button "You Control".
2. Explore and notice that values for x1, y1, and
m can be changed by using the mouse and the scroll bar
directly below. Movement of the bar
to the right raises the value and movement to the left decreases
the value.
3. Change the x1 value to 56.7
Change the y1 value to 69.3
Change m to 1.2
What is the value of the y intercept (where
the x crosses the y axis)? _______
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Change the x1 value to –20.7
Did the y intercept move? ______
If so, describe the movement.
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Change the value of y to –22.5
Did the y intercept move?
If so, describe the movement.
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Change the m value to –2.1
Did the y intercept move?
If so, describe the movement.
What happens to the slope of the line?
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Now manipulate the values of x, and y. Record
in the space provided the values of x and y used and
the value of m for each of these changes.
a) x____ y_____ m____
Did the y intercept move? ______
If so, describe the movement.
b.) x____ y_____ m____
Did the y intercept move? ______
If so, describe the movement.
c.) x____ y_____ m____
Did the y intercept move? ______
If so, describe the movement.
d.) x____ y_____ m____
Did the y intercept move? ______
If so, describe the movement.
e.) x____ y_____ m____
Did the y intercept move? ______
If so, describe the movement.
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Using the back of this paper write 4 paragraphs (minimum
of 3 sentences for each paragraph) using the following leads:
As the value of x is changed what is the effect on
the other 2 variables…
As the value of y is changed what is the effect
on the other 2 variables….
As the value of m is changed what is the
effect on the other 2 variables…
The slope of a line is changed by…
____________CUT HERE________________________________________________________________
Lesson B
Because graphs can be used to show whether data being
measured are directly or inversely proportional to each other, graphs are
one of the best ways to communicate the results of an experiment. If the
data being measured is directly proportional to each other, as one increases
the other will also increase or if one decreases the other will also decrease.
However, if data being measured is inversely proportional to each other,
for example, as one increases, the other will decrease. In this exercise
graphs of directly proportional data will be studied.
If possible, the function to be graphed should be in the
form of a straight line. The general form can represent the equation for
a straight line (a linear equation):
y = mx + b
where y is the dependent variable, x is the independent
variable, m is the slope, and b is the y-intercept.
The independent variable (x) is the mathematical variable
whose value is specified first and determines the value of the dependent
variable.
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The dependent variable (y) is the mathematical variable whose
value is determined by the independent variable. For example, if the volume
of an object is known and its mass is to be measured experimentally, the
volume would be the independent variable and the mass would be the dependent
variable. The mass of the object "depends" on the magnitude of the volume.
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Slope (m) is the upward or downward slant or inclination
of a curve. It is mathematically defined as the "change in y" divided by
the "change in x" (m = D y/D
x) or "rise over run".
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The y intercept (b) is the point where the line intersects
the y axis of the graph--the point where x is zero.
If the slope of a line, the y intercept, and one variable
is known, then the other variable can be determined. For example, when
mass versus volume is graphed, the slope can be used to determine unknown
values of volume for given masses or vice versa.
The equation for this graph (in the form y = mx + b) is
M = (2.70 g/mL)V + 0 or more simply M = (2.70 g/mL) V since the y intercept
(b) is equal to zero. The slope was determined from the graph as follows:
Since D y = y2
- y1 and D x = x2 -x1
D y = 135.0 g - 0.0
g = 135.0 g and D x = 50.0 mL - 0.0 mL = 50.0
mL
Thus
Slope = D y/D
x = 135.0 g/50.0 mL = 2.70 g/mL.
Materials
Vernier "Graphical Analysis" program Centimeter ruler
Scissors String
Miscellaneous cylinders (coins, juice cans, soup cans,
coffee cans, petri dishes)
Procedure
Part A
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LENGTH (cm) VS. LENGTH (in)
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Length (in)
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Length (cm)
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0.0
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0.0
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5.0
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12.7
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10.0
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25.4
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15.0
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38.1
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20.0
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50.8
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25.0
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63.5
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Obtain centimeter graph paper from the instructor. Graph
the data from the table above placing the length in inches on the x-axis
and the length in centimeters on the y-axis.
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Choose an appropriate scale for the graph. Label the axes,
capitalizing the first letter of each word, place units in parentheses.
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Title the graph in the form dependent variable (y-axis) versus
independent variable (x-axis). Place the title in all capital letters.
Place the title at top center of the graph.
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Have the instructor to OK the graph before continuing to
Part B.
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Use this graph to answer the questions at the end of the
experiment as homework.
Part B
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Obtain five (5) various objects from those provided. Choose
objects from small to large. Remember to make all measurements as precisely
as possible in order to get good results.
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Use a centimeter ruler to measure the diameter of the smallest
object to the nearest 0.05 cm and record in the data table provided. Turn
the ruler on its edge to get more precise measurements.
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In order to measure the circumference of the smallest object,
wrap a string around the perimeter of the object and measure the length
of the string to the nearest 0.05 cm. Record the measurements in the data
table.
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Repeat the procedure for the remaining objects going from
smaller to larger.
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When all measurements are complete and recorded, put away
all materials as directed by the instructor.
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Proceed to a computer to graph the data using Graphical Analysis.
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CIRCUMFERENCE VS. DIAMETER
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Object
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Diameter (cm)
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Circumference (cm)
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| 1. |
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| 2. |
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| 3. |
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| 4. |
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| 5. |
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In the Graphical Analysis program, choose File on
the Tool Bar. Choose New and, if asked to save data in memory, choose
No.
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Choose File again on the Tool Bar and choose Printer
Setup. Choose the name box and type in student name(s). Choose date
box for current date. Choose Setup at the bottom of the Printer
Setup window and choose Landscape. Choose OK and OK
again.
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Under the data table window, enter the data for diameter
in the blue X column and the circumference data in the
green Y column. Be sure to enter data from the smallest object
to the largest object.
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Double click on the blue X at the top of the data
column and type the new name for the data column. Push Tab, type
the correct units for the x-axis. Do not use parentheses for the units.
Choose OK.
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Repeat procedure 10 for the green Y column.
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Under the graph window, double click on the title at the
top of the graph and rename it using all capital letters in the form y-axis
versus x-axis. Choose OK.
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Click on anywhere on the graph. On the Tool Bar, choose Graph
and click once on Connecting Lines to turn this option off.
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On the Tool Bar, choose Analyze, choose Automatic
Curve Fit, choose Linear, choose OK, and choose OK-Keep
fit.
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Record the slope and y intercept values for the graph in
the table provided.
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REGRESSION LINE DATA TABLE
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Slope (m)
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y- intercept (b)
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On the Tool Bar, choose File, choose Print,
and choose Selected Display. Type in the number of copies needed
and choose OK.
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When the graph is printed, choose File on the Tool
Bar, choose New, and when asked to save data to memory, choose No.
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Use the printed graph to answer the questions at the end
of the lab for homework.
Analysis
Answer all questions as complete sentences on a
separate sheet of paper! Show all work for problems!
Part A
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Calculate the slope for the graph plotted in Part A. Show
all calculations neatly including the appropriate formula. Include units
in the calculations and the final answer.
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Determine the y-intercept value for the graph.
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What use could be made of the slope value from this graph?
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Use the slope value determined in question 1 to convert 15.5
inches to centimeters.
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Use the slope value to convert 44.7 centimeters to inches.
Part B
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From what has been learned from this activity, define slope
and y-intercept in your own words.
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Using the equation for a straight line, rewrite the equation
substituting C for y, D for x, and the value from the slope of the graph
for m.
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What does the slope of this graph represent?
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What unit(s) would be assigned to this slope value?
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What is the common name that is given to this slope value?
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Use the equation developed in question 2, calculate the diameter
of an object with a circumference of 35.5 cm. Show all work including
the original equation. Isolate the unknown variable before substituting
numerical values into the equation.
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Using the same equation, calculate the circumference of an
object with a diameter of 7.75 cm.
Results/Conclusions
Write a two-paragraph results/conclusions:
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The paragraph for results should include descriptions
of the graphs that were made, the values of slope and y-intercept for Parts
A and B, and the method used to determine slope and y-intercept.
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The paragraph for conclusions should include what was
learned about slope, y-intercept, and proper methods of graphing.
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Discuss advantages/disadvantages for manual graphing versus
computer graphing.
Extension
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PRESSURE VS. VOLUME
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Volume (mL)
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Pressure (atm)
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5.0
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2.02
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7.5
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1.35
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10.0
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1.02
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12.5
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0.81
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15.0
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0.69
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17.5
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0.58
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20.0
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0.50
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A graph with a curve as shown above suggests an inverse
relationship. To confirm an inverse relationship, plot the reciprocal of
one variable versus the other variable. In this case, pressure is plotted
versus the reciprocal of volume, 1/volume. To plot this graph:
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Enter the volume in the x-list and pressure in the y-list.
Follow the directions given in Part B of the lab to label and give the
correct units for the x and y-lists.
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Click on Data on the Tool Bar, choose New Column
and Calculated. Type in Inverse Volume under New Column Name
and 1/mL under New Column Units. To type the formula "1/Volume"
in New Column Formula., use the on-screen keypad to enter 1,
/, and column ¯ , and
choose Volume. Choose OK.
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Double click on the x-axis label, and choose Inverse Volume
and OK.
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Double click on the title and type it in all capital letters.
Click OK when finished.
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Follow the steps for Printer Setup and Printing from Part
B of the lab.
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Write a paragraph explaining the mathematical relationship
between pressure and volume and the mathematical relationship between pressure
and inverse volume by comparing the pressure-volume and pressure-inverse
volume graphs.
______CUT HERE______________________________________________________________________
Modifications:
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Seeing-impaired student's work should be printed on blue
paper.
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Exceptional children may require more time and possibly need
to work with an aide for assistance during lab activities (or paired with
another student).
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Students may need to work in small groups with teacher directed
instruction using a data projector and teacher going step by step with
students as they enter data.
Enrichment Activities: Additional activities
with Graphical Analysis are provided taking students to a different level
of comprehension and difficulty.
Evaluation/Assessment:
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Teacher will grade the worksheets of the students and the
graphs created. Teacher will look for the process of mathematical computation
and unit placement.
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Students will place all work in a folder for their portfolio.
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Classroom participation will also be assessed.
IGOs and other standards:
10.4, 10.8, 10.9, 10.10, 10.11, 10.13, 10.14, 10.15, 10.20, 10.92, 10.93,
and 10.94
10.24, 10.30, 10.87
AM1.1, AM1.11, AM1.17
AM2.3, AM2.5, AM2.13, AM2.15, AM2.16, AM2.18
A1.1, A1.5, A1.9, A1.10, A1.21, A1.22
A2.2, A2.21, A2.22
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Geometry and Applied Geometry
G.17, G.24
National Standards