1. Scientific Method

2. Steps in the Scientific Method
Observation
Hypothesis
Experiment
Data collection
Conclusion
Retest

3. Observations Gathered through your senses
A scientist notices something in their natural world
For example, you may notice that many salamanders near a pond have curved rather than straight tails.

4. Hypothesis Predicts an outcome Must be testable
I think the salamanders have curved tails due to a pollutant in the soil where they live.
Predicts an outcome
Must be testable

5. Experiment A procedure used to test the hypothesis.
Independent variable
Dependent variable
Constants
Control group
Experimental group

6. Independent Variable
The factor that is being changed or tested in an experiment.
Example: One group of salamanders is exposed to a certain pollutant and the other group is not. The tail growth of both groups is monitored for 6 months. Each group is given the same diet and they are all the same age and species of salamander.
Can you identify the independent variable?

7. Dependent Variable Your results!
The outcome… what is being measured or observed.
Example: One group of salamanders is exposed to a certain pollutant and the other group is not. The tail growth of both groups is monitored for 6 months. Each group is given the same diet and they are all the same age and species of salamander.
Can you identify the dependent variable?

8. Constants
Every factor besides the independent variable must remain the same so that you know for sure what has affected your results.
You hypothesize that plants will grow taller in the sunlight. To test this, you set up two groups: one is in the sunlight and given water every day, while plants in the other group are kept in the dark without water. At the end of the experiment, plants in the first group are taller… but was it the sunlight or the water? Or both?

9. Constants
Example: One group of salamanders is exposed to a certain pollutant and the other group is not. The tail growth of both groups is monitored for 6 months. Each group is given the same diet and they are all the same age and species of salamander.
Can you identify some constants?

10. Control Group One group of test subjects is used for comparison.
They do not get exposed to the independent variable.
Example: One group of salamanders is exposed to a certain pollutant and the other group is not. The tail growth of both groups is monitored for 6 months. Each group is given the same diet and they are all the same age and species of salamander.

11. Experimental Group The group that is being tested on.
Example: One group of salamanders is exposed to a certain pollutant and the other group is not. The tail growth of both groups is monitored for 6 months. Each group is given the same diet and they are all the same age and species of salamander.

12. Data Results of the experiment
May be quantitative (numbers) or qualitative
Example: 75% of the salamanders exposed to the pollutant developed curved tails, while only 3% of salamanders in the other group had curved tails.

13. Precision: all measurements or results agree with each other.
Precision vs. Accuracy
Precision: all measurements or results agree with each other.
Accuracy: the measurement or result reflects the correct value.

14. Precision vs. Accuracy

15. Conclusion
The answer to the hypothesis based on data collected from the experiment.
Our data suggested that our hypothesis was correct- pollutants were causing abnormal tail shape in salamanders.

16. Retest In order to verify the results, experiments must be retested.
How can you make an experiment more “valid”?
Retest!
Large sample sizes
Performed by different scientists or groups

17. Scientific Method Identify a problem
State observations about the problem
Form a hypothesis
Design an experiment
Collect data
Form a conclusion
Retest