1. Scientific Method

2. What is Science? Science is a method for studying the natural world.
It is a process that uses observation and investigation to gain knowledge about events in nature.

4. Scientific Method:
Why Bother?

5. Scientific Method
It ensures your experiment will actually answer your question.
It shows the world how you obtained your results.
It allows other scientists to recreate your experiment to support/disprove your conclusions.
It allows other scientists to build and extend on your research

6. Scientific Method:
Start with a Question

7. What makes a good question?
A good scientific question is testable.
Why is there air?
What is the air made of?

8. What makes a good question?
A good scientific question can be tested with some experiment or measurement that you can do.
Where did the universe come from?
How fast does a football fly through the air when I throw it?

9. What makes a good question?
A good scientific question builds on what you already know.
What chemicals are needed to make radishes grow?
What is the source of genetic mutations in drosophila melanogaster?

10. What makes a good question?
A good scientific question is specific and not too broad.
Why do leaves turn brown?
Does the amount of water or sun a plant receives affect the colour of the leaf?

11. What makes a good question?
A good scientific question is related to the topic that is being researched.
If you want to learn about gravity, which would be a
good question?
What materials are best at keeping astronauts warm in space?
How do astronauts’ bodies change when they are in a zero gravity environment?

12. What makes a good question?
A good scientific question could have more than one answer, it is not a simple ‘yes’ or ‘no’ answer.
Do plants grow in the dark?
What lighting conditions are best for plants to grow?

13. What makes a good question?
A good scientific question is one that has scientific value.
How is a planet’s motion influenced by objects around it?
When is my birthday?

14. Why do dogs bark?
How are students’ grades affected by the amount of television watched?
What temperatures cause bacteria to grow the fastest?
What chemicals will prevent cut apples from turning brown?

15. Why are oceans salty?
Is the bounciness of a basketball related to the temperature of the ball?
Is protein synthesis affected when cells are placed in hypotonic solutions?
What types of materials best reduce friction on a skateboard wheel?

16. Is the rate of hair growth affected by the amount of protein someone eats?
Does baking soda and vinegar react?
How often does the sun rise?

17. The Scientific Method
What is a HYPOTHESIS?

18. A hypothesis…
Is a possible explanation or a prediction for an observed cause-effect relationship.
Is developed from the original question in the inquiry/investigation.
Is based on prior knowledge.
Usually written as an “If…..then …..” statement

19. If/As…then…because…
The “If” or “As” part of the statement is the cause variable (independent variable)
The “then” part of the statement is the effect variable (dependent variable)

20. Example #1.
Question: How does temperature (heat energy) affect the rate at which water boils? Hypothesis: If more heat energy is added to water, then the water will come to a boil faster because the water particles will be moving faster.

21. Example #2.
Question: How does the amount of time a student spends studying affect their grades? Hypothesis: If a student studies more, then their marks will improve because they have a better understanding of the material.

22. 1. Why do people who smoke put more salt on their food?
2. How does the amount of sunlight affect the growth of a plant?

23. 3. Why does water evaporate faster when its surface are is increased?
4. Why do plastic lids no longer fit their containers after going through the dishwasher?

24. The Scientific Method
What are VARIABLES?

25. Scientists…
use experiments to search for the cause and effect relationships in nature.
design an experiment so that changes to one item cause something else to vary in a predictable way.

26. These changing quantities are called variables.

27. Independent variable:
The ‘cause’ or ‘manipulated’ variable
Values the experimenter chooses to change
Plotted on the horizontal axis when graphing
Example: if testing the effect of amount of light on the growth of seedling, Independent Variable = Amount of light plant receives

28. Dependent variable: The ‘effect’ or ‘responding’ variable
Varies due to changes in the independent variable
Plotted on the vertical axis when graphing
Eg. Plant Height

29. Controlled variables:
All other conditions that are kept the same
Ensure a ‘fair test’
Eg. type of soil, amount of water, temperature, length of time grown, etc

30. Testing the affect of different liquids on plant growth
Independent Variable:
Dependent Variable:
Control:
Indep – liquids
Depend – height
Control – soil, light, etc

31. How much water flows through a faucet at different openings?
Question
Independent variable
Dependent variable
Controlled variables
How much water flows through a faucet at different openings?
Faucet openings (closed, half-open, fully open)
Amount of water flowing in litres per minute
Same faucet
Same water pressure
Does heating a cup of water allow it to dissolve more sugar?
Does an electric motor turn faster if you increase the voltage?

32. Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they’re supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks. Problem: Smithers thinks that a special juice will increase productivity of workers. Specific question: Will the special juice that Smithers has increase the productivity of workers?
Independent Variable
Dependent Variable
Controlled Variables

33. Homer notices that his shower is covered in a strange green slime
Homer notices that his shower is covered in a strange green slime. His friend Barney tells him that coconut juice will get rid of the green slime. Homer decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of “treatment” there is no change in the appearance of the green slime on either side of the shower. Problem: Homer’s shower is covered in a strange green slime. Specific question: Will coconut juice remove the strange green slime that is covering Homer’s shower?
Independent Variable
Dependent Variable
Controlled Variables

34. How will you test your hypothesis?
Scientific Method
How will you test your hypothesis?

35. Write out your method/procedure
Develop a procedure for a reliable experiment and address safety rules.
Step by step so anyone can follow

36. Scientific Method
Making Observations

37. Are you a good observer?

38. Quantitative Observations:
Contain a measurement of some kind
Will have a number associated with it
Examples:
John has a mass of 70 kg
The volume of the liquid is 250 mL.

39. Qualitative Observations:
Do NOT contain any numbers
Are collected by your SENSES
Examples:
Susan has red hair.
Bob is tall.

40. Indicate whether each of the following is a quantitative or qualitative observation.
The concert was very loud
The water was cold
c. The reaction took 48 seconds to occur
The grass was green
e. The volume of the object was 4.9 L
f. The length of the trip was675 km
g. The sandpaper was rough.
h. The sugar plus sulfuric acid turned black, then grew to the height of 20 cm.

41. Recording Results and Observations
Scientific Method
Recording Results and Observations

42. Observations are best recorded in a table.
Question: How does adding a mass to the end of an elastic band affect its length? Table 1. How the mass of an object affects the length of an elastic band.
Mass of object
(g)
Length of elastic (cm)

43. What makes this a good observation table?
How else could you show these results in a meaningful way?

44. Question: How does the amount of stirring affect the amount of salt that dissolves in a glass of water?

45. Scientific Method
Graphing

46. Line Graphs
Used to track changes over time, particularly over shorter periods of time

47. Bar Graphs
Used to compare things between different groups or to track changes over time.
Best used when changes of time are larger.

48. Pie Chart
Used to compare parts of a whole (parts add up to 100%)

49. X-Y Plot Used to determine relationships between two different things.
X-axis measures on variable and Y-axis measures another.

50. Plotting Graphs
Independent variable is placed on the horizontal axis (x) and the dependent variable is placed on the vertical axis (y).
Determine the range of data and spread the scale as widely as possible.
Number and label each axis and put a title on top of the page (dependent-independent).
Plot each data point and mark it in pencil. Draw a small circle around each dot, and then draw the best straight line or smooth curved line that passes as many points as possible.

51. Graphing Why do scientists use graphs?
For line and bar graphs, the independent variable is plotted on the ___ axis and the dependent variable is plotted on the ___axis
When do you use a line graph?
What is a “line of best fit”? Describe how you draw it.

52. Table: Students Using Recycling Bins
Number of Bins 1 2 3 4
Number of Students using recycling bins 28 36 48 62

54. Bar Graphs
6. When do you use a bar graph? 7. Draw a bar graph using the following data:
Material
Flow Rate (cm/s)
Water 6
Cooking oil 4
Molasses
0.5
Ethanol 5
Ketchup 2

56. Scientific Method
Conclusions

57. Conclusion: A good conclusion should include:
A statement of the purpose
Whether the hypothesis was supported or rejected
A sentence or two summarizing your results, with data
Any problems you may have had
A future experiment that can build on your results
*In a formal conclusion, never use I, we, you, they, she, he…etc.

58. Example:
The purpose of this experiment was to test the new fertilizer, Brand A, on plant growth.
The hypothesis that Brand A would cause plants to grow taller than plants treated with store bought fertilizers was rejected.
Plants treated with Brand A grew 1.5 cm in one week, whereas plants treated with store-bought fertilizer grew 1.9 cm in one week.
One problem that occurred was that Brand A appeared to oxidize when exposed to sunlight, reducing its efficacy. In the future, it would be interesting to apply Brand A at night time to see if application without sunlight results in more effective plant growth.

59. Now your turn:
Purpose: to determine if moisture affects the growth of bacteria
Hypothesis: If bacteria plates are exposed to higher levels of moisture, then more bacteria will grow.

60. Amount of Water Added (mL) Number of Bacteria Colonies
Results:
Plate Number
Amount of Water Added (mL)
Number of Bacteria Colonies 1 5 2 10 7 3 20

61. Conclusion: