Graphing in Science

There are three main types of graphs: Pie Bar What are these graphs trying to communicate? You see numbers and names, but without background we really do not know what these graphs are trying to communicate. Line

Let’s look at an example of how a graph is used...

When a scientist conducts an experiment, he/she carefully observes what is happening. He/She records information called data. Time (s) Temp. (C) 0 s 15 0 30 s 18 0 60 s 20 0 90 s 22 0 The data is often a set of numbers.

#'s It is important for scientists to be able to take data... Such as numbers And make it into a visual “picture” of what the data says... In order to make valid conclusions from experiments...

What does this data look like?

Line graphs take data and give us a picture of what that data looks like: Temperature Time This graph helps us to understand the relationship between time and temperature.

A variable is what “changes” in an experiment. Variables Experiment: You are measuring the temperature in degrees Co of a water sample as it is heated over a period of 30 minutes. changes changes A variable is what “changes” in an experiment.

You need to know how to recognize the To make graphs You need to know how to recognize the independent variables dependent

Experiment: You are measuring the temperature in degrees Co of a water sample as it is heated over a period of 30 minutes. You DECIDE the interval (each minute) to collect data (temperature). Time (min) Temp. (C) Interval you collect data or independent variable The data collected or dependent variable at 0 min 0 0 it is 1 min 0 0 2 min 0 0 3 min 1 0 4 min 5 0

In this table there are two variables: time temperature

Which is the independent variable? time ...is the independent variable because this is the interval you chose to collect data. The scientist “controls” this variable. temperature

Which is the dependent variable? time temperature ...is dependent on the time so the temperature is the dependent variable. This is the data that a scientist collects.

Constructing a graph 1. Determine the independent and dependent variables in your table. 2. Label each axis: x-axis independent and y-axis dependent. 3. Find the variable range: “middle value” is halfway on the graph scale. 4. Number and label the axis. 5. Plot the data points. 6. Connect the data points. 7. Title the graph.

1. Determine the independent and dependent variables in your table. You chose at what “interval” to collect the data. This is information (data) you collected at that interval. time temperature This is the INDEPENDENT Variable. This is the DEPENDENT variable.

2. Label each axis: x-axis independent and y-axis dependent. Temperature Dependent Variable y x Time Independent Variable

7 or 8 needs to be about here... 4. Number and label the each axis. 3. Find the variable range: “middle value” is halfway on the graph scale. low 100 90 80 70 Middle 60 Temp. in C 50 40 30 20 10 7 or 8 needs to be about here... 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Time in Minutes high 4. Number and label the each axis.

Temperature of “Liquid A” as It Is Heated 5. Plot the data points. Temperature of “Liquid A” as It Is Heated 0, 0 1, 0 100 2, 0 90 3, 3 80 4, 14 70 5, 25 60 6, 36 Temp. in C 7, 47 50 8, 58 40 9, 69 30 10, 80 20 11, 91 10 12, 98 13, 98 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14, 98 Time in Minutes 15, 100 6. Connect the data points. 7. Title the graph.

Constructing a graph 1. Decide what the independent and dependent are in your table. 2. Label each axis: x-axis independent and y-axis dependent. 3. Find the variable range: “middle value is halfway on the graph scale. 4. Number and label the each axis. 5. Plot the data points. 6. Connect the data points. 7. Title the graph.