Graphing in Science A picture is worth a thousand words.

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

When to Use A Line Graph: Use when trying to interpret information beyond the known data Interpolation: predicting the data BETWEEN the known points on the graph - Extrapolation: predicting data BEYOND the known points on the graph Temp °C Time in Seconds

When to Use A Bar Graph: Use to show how something changes over time or to compare items. Used especially when collecting data over many weeks or from year to year. # of State Championships High Schools

When to Use A Pie Graph: Use to show percentages of a whole or group. They do NOT represent changes over a period of time. % of Students in SBISD The total of the pie should add up to 100%. Anglo – 58% African – 23% Hispanic – 10% Asian – 9% * Data is pretend.

Let’s look at some examples of how graphs are 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?

Data is a ………. picture for your brain!

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

Experiment #1: 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 the data (temperature). Time (min) Temp. (C) Interval at which you collect your data or independent variable The data being 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

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.

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 Line Graph 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 each 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.

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.

Constructing a Bar Graph Similar to a line graph in determining the independent and dependent variable. Label each axis: x-axis independent (what is being compared)and y-axis dependent (usually the # or value). 3. Determine the name and color/pattern for each bar. 4. Make a legend or a key for the information. 5. Plot the information. 6. Title the graph.

Experiment #2: You are trying to compare the quantity and colors of M&M’s in two different packages. Similar to a line graph in determining the independent and dependent variable. Color Pkg 1 Pkg 2 Red 7 5 Blue 6 8 Orange 10 Green 12 14 Yellow 9 Brown 4 2

Label each axis: x-axis independent (what is being compared) and y-axis dependent (usually the # or value). # of M&M’s Colors of M&M’s

3. Determine the name and color/pattern for each bar. 4. Make a legend or a key for the information. 5. Plot the information. # of M&M’s Colors of M&M’s

Comparison of Colors of M&M’s In 2 Packages 6. Title the graph. Comparison of Colors of M&M’s In 2 Packages # of M&M’s Colors of M&M’s

Constructing a Pie Graph 1. Collect the known data from your resources. 2. Determine the value for each slice of the pie. 3. Name each slice and select a color/pattern for each piece to be represented on the graph. 4. Make the legend / key for the graph. 5. Total the graph – Should add up to 100%. 6. Title the graph.

Experiment #3: You are trying to Compare the relationship among the different high schools in Spring Branch ISD. 1. Collect the known data. Grade Level # of Students MHS 2201 NHS 1740 SSH 1915 SWHS 1947

2. Determine the value for each slice of the pie. HS’s # of Students MHS 2201 NHS 1740 SSH 1915 SWHS 1947 TOTAL 7803 Add up the TOTAL number of all students then divide by that group to get the percentage of students. MHS % = 2201 students 7803 total students MHS % = 0.282 Move decimal point 2 places to the Right = 28% Repeat above steps with the remaining data. HS’s Percentage MHS 28% NHS 22% SSH 25% SWHS TOTAL 100%

3. Make the legend / key for the graph. Name each slice and select a color/pattern for each piece to be represented on the graph. SWHS MHS SSH NHS 3. Make the legend / key for the graph. MHS – 28% NHS – 22% SSH – 25% SWHS – 25%

% of Students at High Schools 4. Total the graph – Should add up to 100%. MHS – 28% NHS – 22% 100% SSH – 25% SWHS – 25% % of Students at High Schools in SBISD 5. Title the graph. MHS – 28% NHS – 22% SSH – 25% SWHS – 25%