Why do we use graphs?

Why do we use graphs?● Graphing shows the relationship between two

variables● Presents the data visually● Allows scientists to easily see trends in data

Types of Graphs● Bar graph

○ Used to compare similar data for several items or events.

○ A bar graph can make clearer how large or small the differences in individual values are.

What is most people’s favorite type of movie?

How many people’s favorite type of movie is action?

Types of Graphs● Line graph

○ Best for continuous change○ A line graph can show change over time or trends in

data

Types of Graphs● Line graph

○ The x-axis shows the independent variable ○ The y-axis shows the dependent variable

The values of the dependent variable depend on what happens in the experiment.

○ The values of the independent variable are set before the experiment takes place.

What is the independent variable?

What is the dependent variable?

How much rainfall in mm occurred from day 6 to day 8?

Types of Graphs● Pie chart

○ Ideal for displaying data that are parts of a whole.○ Data in a pie chart is presented as a percent.

What is the most abundant gas in the air?

What types of data do we graph?

Do you remember the two types of data that can be collected?

Types of Data● Quantitative data is obtained by measuring.

○ Usually a number or value○ Example: The lab table is 1.2 m long

● Qualitative data is obtained by observing.○ Usually a description○ Example: The solution in the beaker is warm.

Quantitative = “quantity”

Qualitative = “quality”

Which type of data?The classroom is cold.

Which type of data?The classroom is 61.5 degrees Fahrenheit.

Which type of data?The bobcat is 110 cm long from head to tail.

Which type of data?Your textbook has a mass of 1.8 kg.

Which type of data?Your backpack is very heavy because it is filled with textbooks for all of your classes.

Which type of data?The solution is cloudy.