Scientific Method

Problem/Purpose

Hypothesis

Experiment

Controls

Variables

Constants

Materials

Procedure

Data and Observations

Analysis

Conclusion

Theory

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, it will

grow taller

then if it is

given no

food at all

Experiment

• The controlled test of a hypothesis

• Contains:

– Constants

– Control group

– Variables

Experiment You want to test the effects of different amounts 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 fertilizer

Group 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

Experiment Your results after 15 days:

Group 3 Group 4 Group 1 Group 2

Experiment

• Constants- things that are the same for all groups

What were your constants in the experiment?

Amount of soil, water, light

Type of plant, soil

Time increments for measuring growth

Experiment

• Control group

– Serves as a standard of comparison

– Contains all the constants, but not the variable

What was the control group in the experiment?

Group 4: received no fertilizer

Experiment

Variables – Independent variable

• What you (the scientist) are changing in the experiment

• Causes the dependent variable to change

• Goes on X (horizontal) axis of graph

What was the independent variable in the experiment?

Amount of fertilizer

Experiment

Variables – Dependent variable

• what you are testing for/measuring

• Is changed by the independent variable

• goes on Y (vertical) axis of graph

What was the dependent variable in the experiment?

Rate of plant growth

Materials

• What you used to conduct the experiment

– What were the materials used in your experiment?

• 4 pots

• 12 cups of soil

• 4 plants

• 3 ½ cups fertilizer

• 60 cups water

• Light source

Procedure

• Procedure- a logical procedure in solving the problem that is listed in numerical step format.

– Write out the procedure, listing steps in numerical order

1. Fill each pot with 3 cups soil

2. …

Data and Observation

• Recording 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

Data and Observation

Group # Amount of fertilizer (cups)

Plant height (cm)

1 1 10

2 1/2 6

3 2 15

4 0 5

Plant height after 15 days

Analysis

• Graphing guidelines

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

– Label the Y and X axis

• DRY- Dependent/Responding variable on Y-axis

• MIX- Manipulated/Independent variable X-axis

Analysis

• Graphing guidelines

– the entire area of the graphing space should be used (determine appropriate increments)

– Indicate units of measure

Plant growth based on the amount of fertilizer

given over a 15 day time period

The amount of plant fertilizer

Pla

nt g

row

th in

centim

eters

Group 1 Group 2 Group 3 Group 4

O

2

4

6

8

10

12

14

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 repeated and varying 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.