1. Methods of Biology
The series of steps used by scientists to gather information and answer questions is called the Scientific Method.
If you had a question or a problem to solve, what steps would you go through to resolve it?

2. 7 Steps of the Scientific Method
Number 1 - State the Problem
Take note of something no one has seen before or has yet to explain

3. 7 Steps of the Scientific Method
Number 2 - Gather Information
Observation - Gathering information using your senses
Information gathered should be:
Credible - trustworthy
Accurate - correct – based on supported data
Relevant - applicable, related to the topic of the investigation
These sources could be
Previous scientific investigations
Science journals
Textbooks
Other credible sources, such as scientifically reliable internet sites.

4. Observation vs. Inference
Inference – making a judgment based upon an observation and past experience
Fact or Fiction?

5. Make at least 3 observations about this picture.
Make at least 3 inferences about this picture.

6. Make three observations and inferences with this new information
Does the new information change your responses?

7. What does this final picture do to your previous inferences?

8. What does this picture do to your previous inferences?

9. 7 Steps of the Scientific Method
Number 3 - Form a Hypothesis
Create a testable explanation for the situation that you observed

10. 7 Steps of the Scientific Method
Number 4 - Test the Hypothesis - Experiment
Design an experiment
An organized procedure for collecting information under controlled conditions
The experiment will have two groups
Control – all conditions are kept the same
Experimental – conditions match that of the control except for the one factor being tested

11. 7 Steps of the Scientific Method
Testing…
An important part in the experiment design is the sample size – the number of test subjects
A large sample size increases the reliability of results
A large sample size decreases the effect of errors on the outcome
How could having a larger sample size help the following experiments?
Tim tested the effect of fertilizer on two plants The one with fertilizer grew taller than the one without it.
Suzy developed a drug to lower cholesterol She gave it to two patients who later died.

12. 7 Steps of the Scientific Method
Testing…
The condition that is changed in the experiment is the independent variable – it will be the only thing that can affect the outcome
The outcome observed is the dependent variable – it depends upon the changes made to the independent variable
Note: Some experiments cannot be controlled so other observation methods have to be used
Example: wildlife study

13. Independent vs. Dependent Variables
Mark the dependent and independent variable in each situation
Suzy wanted to test how changing her diet affected her weight.
The track team members that ran extra laps at practice ran better times at the next meet.
Jack planted half of his roses in the shade and the other half in the direct sunlight and measured the differences in plant height and bloom production.

14. 7 Steps of the Scientific Method
Number 5 - Record and Analyze Data
Record Data
Data – information obtained from experiments
Observations
Results
Data should be precise and accurate
Precision – the degree to which measurements made in the same way agree with each other
If you and I measure it, do we get the same thing?
Accuracy – the degree to which the value measured agrees with the true or accepted value
Even if we both got the same thing, did we measure it correctly?
Data must then be analyzed or interpreted
Graphs
Tables
Charts

15. 7 Steps of the Scientific Method
Number 6 - State a Conclusion
Did the data support the hypothesis?
If yes…
Verify results
Can the experiment be repeated?
Do other scientists support the findings?
If no…
Repeat the experiment
Revise the experiment
Develop a new hypothesis
Always Report Results!

16. 7 Steps of the Scientific Method
Number 7 - Repeat
No matter what happened!
Fact – Observable phenomenon that can be confirmed by scientists many times
Form a Theory – a hypothesis tested over a long period of time, supported by separate experiments

17. Fact vs. Theory Which is Fact…Which is Theory?
Dinosaurs were cold blooded.
The caterpillar is 3.5 cm long.

18. Using the Scientific Method
You haven’t been catching as many fish as you used to at your best fishing spot
Your friend tells you that you and your brother smell funny

19. Identifying Study Components
A student noticed that when a dog is cut, the dog periodically licks its wounds. Usually after a few days, the wound begins to heal without ever showing signs of infection. The following steps outline the student's line of reasoning:
I wonder why the dog's wound doesn't become infected.
The dog's saliva must prevent the growth of infection-causing bacteria.
I'll obtain a bacterial culture and grow the same kind of bacteria in two identical culture dishes. Once the bacteria start growing, I'll add dog saliva to only one of the dishes and leave the other alone. I'll cover both dishes. Then I'll observe what happens each day for a week.
Even after adding the dog saliva to one of the dishes, the bacteria continued to grow in both dishes over the course of the week. However, the bacteria in the treated dish grew more slowly than the bacteria in the untreated dish.
I think I'll try something else. I'll start with two identical culture dishes, as before, and use the same kind of bacteria in each dish, but this time I'll treat one dish with dog saliva before I add the bacteria. I'll observe what happens each day for a week.
What was the student’s hypothesis?
Which step described the experimental set up?
Identify the control
What is the independent variable?
What is the dependent variable?
What data did the student collect?
What is a possible conclusion from this experiment?
Is that conclusion a fact or an inference?

20. Identifying Study Components
A student noticed that when a dog is cut, the dog periodically licks its wounds. Usually after a few days, the wound begins to heal without ever showing signs of infection. The following steps outline the student's line of reasoning:
I wonder why the dog's wound doesn't become infected.
The dog's saliva must prevent the growth of infection-causing bacteria.
I'll obtain a bacterial culture and grow the same kind of bacteria in two identical culture dishes. Once the bacteria start growing, I'll add dog saliva to only one of the dishes and leave the other alone. I'll cover both dishes. Then I'll observe what happens each day for a week.
Even after adding the dog saliva to one of the dishes, the bacteria continued to grow in both dishes over the course of the week. However, the bacteria in the treated dish grew more slowly than the bacteria in the untreated dish.
I think I'll try something else. I'll start with two identical culture dishes, as before, and use the same kind of bacteria in each dish, but this time I'll treat one dish with dog saliva before I add the bacteria. I'll observe what happens each day for a week.
What was the student’s hypothesis?
Which step described the experimental set up?
Identify the control
What is the independent variable?
What is the dependent variable?
What data did the student collect?
What is a possible conclusion from this experiment?
Is that conclusion a fact or an inference?