1. Scientific Method

2. Observation vs Inference
Observation … notice or perceive
Ex: “The dolphin has a scar.”
Inference ... judgment based on observation
Ex: “The dolphin’s scar is a healed injury caused by a boat propeller.”

3. Qualitative vs. Quantitative data
Qualitative – Thoughts, observations, opinions, or other data expressed in words
Quantitative - Information that can be expressed in numerical terms, counted, or compared on a scale.
“It was colder on October 1st than it was on October 5th”

4. Practice
Observation or Inference? 1) White fur helps snow rabbits hide. 2) Insects have six legs. Qualitative or Quantitative Observation? 1) The eagle’s wing span was 7ft. 2) The cheetah runs very fast.

5. Steps in the Scientific Method
Observation
Hypothesis
Experiment
Data Collection
Conclusion
Retest

6. Observations Gathered through your senses
A scientist notices something in their natural world

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

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

9. 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.

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

11. Experiment
Variable – factor in the experiment that is being tested

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

13. More on Hypothesis
Remember, a hypothesis is an educated guess about how things work.
Most of the time a hypothesis is written like this: "If _____[I do this] _____, then _____[this]_____ will happen."

14. Hypothesis
Your hypothesis should be something that you can actually test, what's called a testable hypothesis. In other words, you need to be able to measure both "what you do" and "what will happen."

15. Hypothesis Example #1
"If I open the faucet [faucet opening size is the independent variable], then it will increase the flow of water [flow of water is the dependent variable].

16. Hypothesis example #2
"If a plant receives fertilizer [having fertilizer is the independent variable], then it will grow to be bigger than a plant that does not receive fertilizer [plant size is the dependent variable]."
What is the independent variable?
fertilizer
What is the dependent variable?
Plant size

17. Hypothesis example #3
"Raising the temperature of a cup of water [temperature is the independent variable] will increase the amount of sugar that dissolves [the amount of sugar is the dependent variable].“
What is the dependent variable?
Amount of sugar
What is the independent variable?
temperature

18. Which is the better hypothesis?
Aphid-infected plants that are exposed to ladybugs will have fewer aphids after a week than aphid-infected plants which are left untreated.
Ladybugs are a good natural pesticide for treating aphid infected plants.

19. What makes a good hypothesis?
For a GOOD hypothesis,
Answer “Yes” to every question
Is the hypothesis based on information in the Research paper?
Yes/ No
Does the hypothesis include the independent and dependent variables?
Yes/No
Have you worked the hypothesis so that it can be tested in the experiment?

20. Controls and Variables

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

22. 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.

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

24. 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.

25. 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.

26. 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.

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

28. Valid Experiments

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

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

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

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

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

34. Review

35. 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