Graphing

Parts of a Graph• Title – What is the graph about?• X- axis – usually the Independent variable (what is

being compared or changed) WITH UNITS

• Y- axis – usually the Dependent variable

(what is being measured – the numbers) WITH UNITS

• Data – information being observed

Bar Graphs• Used when data is a one time measurement.

This means that each variable is not measured continuously. (Qualitative)

• Used to compare different types of events or ideas in the same conditions.

• Examples: Activities vs. participants, light conditions vs. plant growth.

Data Table for Bar Graph

After School Activities

Number of Students

Watch TV 40

Talk on the phone 50

Hang out with friends 38

Complete homework 16

Earn money 35

Line Graphs• Used to show patterns and trends over a period of

time. (Quantitative)• Connects the data points to help show those

changes.

• Examples: Temperature changes, population growths

Data Table for Line Graph

Average RainfallTime (Months)

2 3 4 5 6 7 8 9

Rainfall (mL)

15 21 28 24 16 8 2 1 3

Comparative Line Graphs• Used to compare two or more sets of data.

• These graphs will have the same labels, but different sets of data on them. Each different data set needs to be in its own color with a legend.

• Examples: Comparing the average temperature for each month over a few years, a student’s grades in four subjects throughout their junior high experiences.

Data Table for Comparative Line

GraphYear 1967 1977 1987 1997 2007

# of Females

100 250 300 600 650

# of Males 650 750 700 600 550

Number of Science Majors in College

Circle Graphs• Used to illustrate different parts of a whole unit.

• The graph is usually color coordinated with a legend, and the percent of each unit written in the graph.

• Examples: Number of blue, green or brown eyed students in the class, amount of spending money in a family budget.

Graph this data

Day 1 2 3 4 5

Total Growth of plant

4 cm 6 cm 10 cm 11 cm 13 cm

Graph this data

• An experiment was performed to measure the pH level of the soil when a plant was given different levels of light to grow.

• Different light levels were accomplished by placing mesh screens over the light source. (more screens=darker)

• Set up a graph and label the x-axis and y-axis of the graph.

Graph this data

• The following data was collected for the previous experiment. 2 plants were used for each light level.

Light Level Plant # pH of soil

0 screens 1 6.5

2 6.1

2 screens 1 6.9

2 7.5

4 screens 1 7.3

2 7.7