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

4. Observations
An example of an observation might be noticing that many salamanders near a pond have curved, not straight, tails

5. Hypothesis A suggested solution to the problem. Must be testable
Sometimes written as If…Then… statements
Predicts an outcome

6. Hypothesis
An example of a hypothesis might be that the salamanders have curved tails due to a pollutant in the moist soil where they live.

7. A procedure to test the hypothesis.
Experiment
A procedure to test the hypothesis.

8. Variable – factor in the experiment that is being tested

9. A good or “valid” experiment will only have ONE variable!

10. Controls and Variables

11. Scientific Experiments Follow Rules
An experimenter changes one factor and observes or measures what happens.

12. The Control Variable
The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome.
Those factors are called control variables.

13. What is the Purpose of a Control?
Controls are NOT being tested
Controls are used for COMPARISON

14. Other Variables
The factor that is changed is known as the independent variable.
The factor that is measured or observed is called the dependent variable.

15. Example of Controls & Variables
For example, suppose you want to figure out the fastest route to walk home from school.
You will try several different routes and time how long it takes you to get home by each one.
Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

16. What are the Variables in Your Experiment?
Varying the route is the independent variable
The time it takes is the dependent variable
Keeping the same walker throughout makes the walker a control variable.

17. One more thing… it is best to make several trials with each independent variable.

18. Valid Experiments

19. Remember: To be a Valid Experiment:
Two groups are required --- the control & experimental groups
There should be only one variable

20. Data Results of the experiment
May be quantitative (numbers) or qualitative

21. Data
Must be organized
Can be organized into charts, tables, or graphs

22. Conclusion
The answer to the hypothesis based on the data obtained from the experiment

23. In order to verify the results, experiments must be retested.

24. Measurement Scientific investigations usually require measurements.
All scientists use a consistent measurement system; SI (System International) or the metric system

25. Units of Metric Measurement
Length: linear distances
Millimeter (mm); centimeter (cm); meter (m); kilometer (km)
Mass: the measure of how much matter something has
Matter is defined as anything that takes up space and has mass
Gram (g); kilogram (kg); metric ton

26. Units of Metric Measurement
Volume and area:
Area is the amount of surface within a set of boundaries; square units of length (m2)
Volume is the amount of space occupied by an object; depends on the type of object
Solids are measured in cubic units (m3)
Liquids are measured in milliliters or liters; mL or L.

27. Units of Metric Measurement
Density: the measure of the amount of matter that takes up a certain space
Mass divided by volume
Grams per cubic centimeter (g/cm3)
Time: measured in seconds or minutes
Temperature: usually in Celsius
Kelvin is the official SI unit for temperature
Absolute zero is -273oC or 0K

28. Review

29. Solving a Problem 1)Identify a Problem
2) State Observations about the problem
3) Form a Hypothesis about the problem (if…then…)
4) Design an Experiment to test the hypothesis
5) Collect Data
6) Form a Conclusion
7) Retest

30. Learning Targets
Compare and contrast independent and dependent variables.
Discuss the parts of the scientific method
Discuss the units of the metric system