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Graphing GuidelinesGraphing Guidelines
Often the goal of an experiment is to find the Often the goal of an experiment is to find the relationship between two variables. relationship between two variables.
As one variable changes, so does the other. As one variable changes, so does the other. Graphing is a useful way to visualize and Graphing is a useful way to visualize and
describe these relationships. describe these relationships. Because the use of graphs is so common in Because the use of graphs is so common in
sciences, it is important for you to know how to sciences, it is important for you to know how to construct and interpret graphs. construct and interpret graphs.
When preparing graphs for this class, keep the When preparing graphs for this class, keep the following guidelines in mind:following guidelines in mind:
Graphing GuidelinesGraphing Guidelines
1.1. It is done on It is done on graphgraph paper. paper.2.2. Use the Use the x-axisx-axis for the independent variable (the for the independent variable (the
variable changed by the experimenter) and the variable changed by the experimenter) and the y-axisy-axis for the dependent variable (the variable for the dependent variable (the variable being measured).being measured).
3.3. The scale you select should be The scale you select should be easyeasy to work with to work with such as one square represents 1, 2, 5, or 10 or such as one square represents 1, 2, 5, or 10 or five squares represents a unit of 1, 10, or a five squares represents a unit of 1, 10, or a multiple of ten (20, 100, 0.1). Never multiple of ten (20, 100, 0.1). Never changechange the the scale along an axis. However, you may use a scale along an axis. However, you may use a differentdifferent scale for each axis. scale for each axis.
Graphing GuidelinesGraphing Guidelines
4.4. Select a scale that uses the Select a scale that uses the greatestgreatest portion of the paper. Leave enough room portion of the paper. Leave enough room to title your axis and graph.to title your axis and graph.
5.5. Label what the axes represent by including Label what the axes represent by including the the measurementmeasurement and its and its unitsunits. For . For example: "Length (cm)" or “Time in example: "Length (cm)" or “Time in seconds”seconds”
Graphing GuidelinesGraphing Guidelines
6.6. For line graphs, plot your points. For line graphs, plot your points. Sometimes you will be asked to connect Sometimes you will be asked to connect the dots. the dots.
• Other times you will be asked to draw the Other times you will be asked to draw the line line of of best fitbest fit. The line should pass as close as . The line should pass as close as possible to each of the points but should not possible to each of the points but should not be connected point-to-point. If the relationship be connected point-to-point. If the relationship appears to be appears to be linearlinear, the line of best fit should , the line of best fit should be a straight line.be a straight line.
Graphing GuidelinesGraphing Guidelines
7.7. TitleTitle the graph. Make sure you describe the graph. Make sure you describe what is represented on the horizontal and what is represented on the horizontal and vertical axes.vertical axes.
8.8. If you are plotting more than one curve on If you are plotting more than one curve on the same graph, include a the same graph, include a legendlegend that that identifies the curves. Use different colors identifies the curves. Use different colors or different types of lines such as solid or or different types of lines such as solid or dashed lines between them.dashed lines between them.
Example GraphsExample Graphs
Practice GraphsPractice Graphs
Recall that a bar graph is useful for Recall that a bar graph is useful for comparing information collected by comparing information collected by counting. We are going to use the clothing counting. We are going to use the clothing of students in this classroom to demonstrate of students in this classroom to demonstrate how to make a data table and bar graph. how to make a data table and bar graph. We will look at the shirt color of boys and We will look at the shirt color of boys and girls in the room.girls in the room.
Practice GraphsPractice Graphs
Step 1: Gather DataStep 1: Gather Data An easy way to An easy way to
organize our data is to organize our data is to create a table. Let’s create a table. Let’s use this table to fill in use this table to fill in our data. our data.
ColorColor # of Boys# of Boys # of Girls# of Girls
RedRed
BlackBlack
GreyGrey
BlueBlue
WhiteWhite
MultiMulti
OtherOther
Practice GraphsPractice Graphs
Step 2: Create the GraphStep 2: Create the Graph
Independent variable (x-axis): ________Independent variable (x-axis): ________
Dependent variable (y-axis): __________Dependent variable (y-axis): __________
Choose two different colors to use (one to Choose two different colors to use (one to represent boys, one to represent girls).represent boys, one to represent girls).
Key Features of Bar GraphsKey Features of Bar Graphs
1.1. TitleTitle
2.2. Axis are labeled with unitsAxis are labeled with units
3.3. Legend Legend
Check your graph to make sure you have these three featuresCheck your graph to make sure you have these three features
Line GraphsLine Graphs
Recall that line graphs are useful for showing Recall that line graphs are useful for showing trends. trends.
Problem:Problem: In an experiment, you check the air temperature at In an experiment, you check the air temperature at
certain hours of the day. At 8 A.M., the certain hours of the day. At 8 A.M., the temperature is 27 temperature is 27 ○○C; at 10 A.M., the temperature C; at 10 A.M., the temperature is 30 is 30 ○○C; at noon, the temperature is 32 C; at noon, the temperature is 32 ○○C; at 2 C; at 2 P.M., the temperature is 31P.M., the temperature is 31○○C; and at 4 P.M., the C; and at 4 P.M., the temperature is 30 temperature is 30 ○○C. Graph the results of your C. Graph the results of your experiment.experiment.
