Scientific Method

Scientific MethodProblem/PurposeHypothesisExperiment

ControlsVariablesConstants

MaterialsProcedureData and ObservationsAnalysisConclusionTheory

Problem/Purpose• Identify what

it is you want to investigate, usually based on something you’ve observed

Do plants need food to

grow?

Hypothesis• What you think will

happen• It is a testable

explanation for an observation

• Sometimes given in the

“If…… then…..” format

If a plant is given more food, then

it will grow taller than

if it is given no

food at all.

Experiment• The controlled test of a hypothesis• Contains:

– Constants– Control group– Variables

ExperimentYou want to test the effects of different kinds of fertilizer

(food supplement) on plant growth. You create an experiment using 4 plant setups. All plants are the same and are planted in 3 cups of the same potting soil. They are given 1 cup of water daily and are given 8 hours of sun every day.

Group 1 is given 1 cup of plant fertilizerGroup 2 is given ½ cup of plant fertilizer Group 3 is given 2 cups of plant fertilizer Group 4 is given no fertilizer at all.

Their length is measured every 5 days.

Set-up of controlled experiment:

Group 1 Group 2 Group 3 Group 4

Experiment

ExperimentYour results after 15 days:

Group 3 Group 4Group 1 Group 2

ExperimentConstants- things that are the same

for all groups

What were your constants in the experiment?

Experiment• Control group

– serves as a standard of comparison– Contains all constants but not the

variable

What was the control group in our experiment?

Experiment• Variables

– Dependent variable- what you are testing for/measuring (goes on y axis)

– Independent variable- what the dependent is dependent upon OR what you are changing in the experiment (goes on x axis)

• What were you measuring/testing for in your experiment?– That is your dependent variable

• What were you manipulating?– That is your independent variable

Materials and Procedure• Materials- what you use to conduct

the experiment– What were the materials used in your

plant experiment?• Procedure- a logical procedure in

solving the problem that is listed in numerical step format.

Data and Observation• What happened during the

experiment• Includes the results in the form of

data• Data should be included as charts,

tables and graphs• Make sure all data tables have a

title and are labeled

Analysis• Graphing guidelines

– Include a title indicating variables (what exactly does this chart show the reader)

– Label the X and Y axis including units– MIX- Manipulated/Independent variable X-

axis– DRY- Dependent/Responding variable on

Y-axis

Plant growth based on the amount of fertilizer given over a 15 day time period

The amount of plant fertilizer given

Plant growth in inches

Group 1 Group 2 Group 3 Group 4

O in.

2 in.

4 in.

6 in.

8 in.

10 in.

12 in.

14 in.

Conclusion• Addresses the hypothesis• Shows that the data supported or

disproved your hypothesis• Make a clear relationship between

the problem and results• Demonstrate a connection

between the experiment and the larger context of form as it relates to function

• Make predictions on other tests that may also be effective

Theory• Theory-

– Explanation for observations proven through experimentation

– Unifying explanation for a broad range of observations

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. 

Identify the:Control Group

Independent Variable

Dependent Variable

What should Smithers' conclusion be?

How could this experiment be improved?

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 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. 

What was the initial observation?

Identify the-Control Group

Independent Variable

Dependent Variable

What should Homer's conclusion be?

Bart believes that mice exposed to microwaves will become extra strong (maybe he's been reading too much Radioactive Man). He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. he found that 8 out of 10 of the microwaved mice were able to push the block away. 7 out of 10 of the non-microwaved mice were able to do the same.

Identify the-Control Group

Independent Variable

Dependent Variable

What should Bart's conclusion be?

How could Bart's experiment be improved?

               Krusty was told that a

certain itching powder was the newest best thing on the market, it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes.

Identify the-Control Group

Independent Variable

Dependent Variable

Explain whether the data supports the advertisements claims about its product.

Lisa is working on a science project. Her task is to answer the question: "Does Rogooti (which is a commercial hair product) affect the speed of hair growth". Her family is willing to volunteer for the experiment.

Describe how Lisa would perform this experiment. Identify the control group, and the independent and dependent variables in your description.