1. The Scientific Method

3. Objectives I will be able to:
Identify the different parts of the scientific method
Write a scientific procedure
Apply the use of the scientific method to common problems

4. Purpose of scientific method
Used to explain things we see

5. Based on observations about something in the natural world
Step 1: Ask a Question
Based on observations about something in the natural world

6. Observations/Identify a Problem
Example of an Question-
Why do some students have higher test scores than others?

7. Step 2: Hypothesis
A possible answer to the question.
Must be testable

8. Step 2: Hypothesis If independent variable, then dependent variable
What is a possible answer to the question, “Why do some students have higher test scores than others?”

9. Step 2: Hypothesis If independent variable, then dependent variable
If students study for more time,
then their test scores are higher

10. A procedure to test the hypothesis.
Step 3: Experiment
A procedure to test the hypothesis.

11. Experiment Variable – factor in the experiment that is being tested
A good or “valid” experiment will only have ONE testable thing
Why?

12. Independent variable – what I control
Experiment
Independent variable – what I control

13. Independent variable – what I control
Experiment
Independent variable – what I control
Dependent variable – what is being measured; depends on changes in the independent variable

14. Experiment Example: test score and time spent studying
Independent variable – time spent studying (I control)
Dependent variable – test score (depends on time spent studying)

15. Experiment
Control Group – the group doesn’t get independent variable

16. Experiment Control Group – the group doesn’t get independent variable
Experimental Group – the group(s) being tested; receives different amounts of independent variable

17. Example Study Time vs. Test Score 5 kids do not study for a test
5 students study for 30 minutes
Control Group – the group which is NOT being tested (5 kids that don’t study)
Experimental Group – the group(s) being tested (5 students who study)

18. 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.

19. What are the Variables in Your Experiment?
Varying the route is the independent variable (I Control!)
The time it takes is the dependent variable
Keeping the same walker throughout makes the walker a control variable.

20. What does your data show?
Step 4: Analyze Data
What does your data show?

21. Step 5: Interpret Data & Draw Conclusion
Does your data support your hypothesis?
Hypothesis can’t be proven! Only supported or not supported!

22. Retest
You can do the experiment many times to make sure the results are accurate.

23. Step 6: Share Results Share results with other scientists
Include very specific procedure
Why?

24. I Do
 You like to garden, and notice that some tomatoes are bigger than others and wonder why. You think that one group is bigger because it receives more sunlight than the others. You decide to split the tomatoes up into 2 groups. Everything between the tomatoes is the same, but one group gets no sunlight, and the other gets 6 hours of sunlight a day. You find that the group that gets more sunlight grows larger than the group that receives no sunlight.

25. I Do Question: why are some tomatoes are bigger than others?
Hypothesis:

26. I Do Question: why are some tomatoes are bigger than others?
Hypothesis: if tomatoes get more sunlight, then they grow bigger
Independent variable:

27. I Do Question: why are some tomatoes are bigger than others?
Hypothesis: if tomatoes get more sunlight, then they grow bigger
Independent variable: amount of sunlight
Dependent variable:

28. I Do Question: why are some tomatoes are bigger than others?
Hypothesis: if tomatoes get more sunlight, then they grow bigger
Independent variable: amount of sunlight
Dependent variable: size of tomatoes
Control group:

29. I Do Question: why are some tomatoes are bigger than others?
Hypothesis: if tomatoes get more sunlight, then they grow bigger
Independent variable: amount of sunlight
Dependent variable: size of tomatoes
Control group: tomatoes with no sunlight
Experimental group:

30. I Do Question: why are some tomatoes are bigger than others?
Hypothesis: if tomatoes get more sunlight, then they grow bigger
Independent variable: amount of sunlight
Dependent variable: size of tomatoes
Control group: tomatoes with no sunlight
Experimental group: tomatoes with sunlight
Result:

31. I Do Question: why are some tomatoes are bigger than others?
Hypothesis: if tomatoes get more sunlight, then they grow bigger
Independent variable: amount of sunlight
Dependent variable: size of tomatoes
Control group: tomatoes with no sunlight
Experimental group: tomatoes with sunlight
Result: hypothesis supported!

32. We Do
 You notice that your friend’s goldfish is much bigger than yours. You both feed it the exact same food in the same amount. You believe that his goldfish is bigger because it lives in a bigger tank. You buy 2 new goldfish, feed them the exact same thing in the same amount and put them in the same water. One is put in a small bowl. The other is put in a big bowl. The one in the big bowl grows to be twice as big.

33. We Do Question: Hypothesis: Independent variable: Dependent variable:
Control group:
Experimental group:
Result:

34. We Do
Question: Why is one fish bigger than the other
Hypothesis:

35. We Do Question: Why is one fish bigger than the other
Hypothesis: If fish live in bigger bowls, then they grow bigger
Independent variable:

36. We Do Question: Why is one fish bigger than the other
Hypothesis: If fish live in bigger bowls, then they grow bigger
Independent variable: bowl size
Dependent variable:

37. We Do Question: Why is one fish bigger than the other
Hypothesis: If fish live in bigger bowls, then they grow bigger
Independent variable: bowl size
Dependent variable: fish size
Control group:

38. We Do Question: Why is one fish bigger than the other
Hypothesis: If fish live in bigger bowls, then they grow bigger
Independent variable: bowl size
Dependent variable: fish size
Control group: fish in small bowl
Experimental group:

39. We Do Question: Why is one fish bigger than the other
Hypothesis: If fish live in bigger bowls, then they grow bigger
Independent variable: bowl size
Dependent variable: fish size
Control group: fish in small bowl
Experimental group: fish in big bowl
Result:

40. We Do Question: Why is one fish bigger than the other
Hypothesis: If fish live in bigger bowls, then they grow bigger
Independent variable: bowl size
Dependent variable: fish size
Control group: fish in small bowl
Experimental group: fish in big bowl
Result: hypothesis supported!

41. You Do In Pairs
I really like when my mom makes cheeseburgers, but I always feel sick afterwards. I believe the cheese is what makes me sick. My mom makes a new batch of burgers, 5 with cheese, and 5 without. I find that when I eat the regular hamburger, I don’t feel sick afterwards.

42. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis:

43. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis: If there is cheese, then I’ll get sick
Independent variable:

44. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis: If there is cheese, then I’ll get sick
Independent variable: Cheese
Dependent variable:

45. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis: If there is cheese, then I’ll get sick
Independent variable: Cheese
Dependent variable: Sickness
Control group:

46. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis: If there is cheese, then I’ll get sick
Independent variable: Cheese
Dependent variable: Sickness
Control group: Burgers without cheese
Experimental group:

47. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis: If there is cheese, then I’ll get sick
Independent variable: Cheese
Dependent variable: Sickness
Control group: Burgers without cheese
Experimental group: burgers with cheese
Result:

48. You Do In Pairs
Question: Why do I feel sick after eating cheeseburgers?
Hypothesis: If there is cheese, then I’ll get sick
Independent variable: Cheese
Dependent variable: Sickness
Control group: Burgers without cheese
Experimental group: burgers with cheese
Result: hypothesis supported!

49. Writing a Procedure
Procedure is a step by step explanation of how you do an experiment
Should look like a recipe

50. Writing a Procedure
Why is a good procedure necessary?

51. Writing a Procedure Why is a good procedure necessary?
So other scientists can recreate experiment exactly!

52. Tips for Writing Procedure
Be very specific
Someone should be able to recreate your experiment exactly
Number the steps

53. Tips for Writing Procedure
Include units, if necessary
Include diagrams, if necessary

54. Graphing Data

55. Graphing Data
Graphing is used by scientists to display the data that is collected during an experiment

56. Graph Title
Graph title - used to describe what the graph is about

57. Independent Variable IV – what I control; goes on x-axis

58. Dependent Variable
DV – what you’re measuring; depends on independent variable; goes on y-axis
Dependent variable

59. Scaling
Scaling – make each box on your axis worth the same amount

60. Key key – information telling you what each bar or point means KEY
= 1 plant measured

61. Key

62. Key key – information telling you what each bar or point means KEY
= 1 plant measured

63. When Should I Use Certain Graphs?
Bar graph – when comparing amounts of different groups or times something happens

64. When Should I Use Certain Graphs?
Line graph – shows how things change over TIME

65. When Should I Use Certain Graphs?
Line graph – when independent variable is time