Scientific Method

The scientific method is a

way to ask and answer

scientific questions by

making observations

and doing experiments.

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Steps of the Scientific Method 1 – 3

1. Ask a Question: The scientific method starts when you ask a

question about something that you observe: How, What, When,

Who, Which, Why, or Where?

And, in order for the scientific method to answer the question it must

be about something that you can measure, preferably with a

number.

2. Do Background Research: Rather than starting from scratch in

putting together a plan for answering your question, you want to be

a savvy scientist using library and Internet research to help you find

the best way to do things and insure that you don't repeat mistakes

from the past.

3. Construct a Hypothesis: A hypothesis is an educated guess about

how things work:

"If _____[I do this] _____, then _____[this]_____ will happen." You must

state your hypothesis in a way that you can easily measure, and of course, your hypothesis should be constructed in a way to help you answer your original question.

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Steps of the Scientific Method 4 – 6

4. Test Your Hypothesis by Doing an Experiment: Your experiment

tests whether your hypothesis is true or false. It is important for your

experiment to be a fair test. You conduct a fair test by making sure

that you change only one factor at a time while keeping all other

conditions the same. You should also repeat your experiments

several times to make sure that the first results weren't just an

accident.

5. Analyze Your Data and Draw a Conclusion: Once your experiment is complete, you collect your measurements and

analyze them to see if your hypothesis is true or false. Scientists often

find that their hypothesis was false, and in such cases they will

construct a new hypothesis starting the entire process of the

scientific method over again. Even if they find that their hypothesis

was true, they may want to test it again in a new way.

6. Communicate Your Results: To complete your project you will

communicate your results to others in a final report and/or a display board. Professional scientists do almost exactly the same thing by

publishing their final report in a scientific journal or by presenting

their results on a poster at a scientific meeting.

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The Process Even though we show the

scientific method as a

series of steps, keep in

mind that new information

or thinking might cause a

scientist to back up and

repeat steps at any point

during the process.

A process like the scientific

method that involves such

backing up and repeating

is called an iterative

process.

Throughout the

process of doing

your lab project,

you should keep a

journal containing

all of your

important ideas

and information.

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Science is ultimately based on

observation (perceiving objects or events using one of the five

senses)

Observations often lead to

questions ---> which lead to experiments to answer the

questions.

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Hypothesis

Is a suggested solution to the problem / question.

Must be testable

Sometimes written as If…Then… statements

Predicts an outcome

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Examples:

Correctly Worded:

1. If plants are given

Miracle grow, then

they will grow taller.

2. If given math tests,

then girls will score

higher than boys.

3. If hermit crabs have

a choice, then they

will choose colorful

shells over drab

shells.

Poorly Worded:

1. Plants will grow

better when given

Miracle Grow.

2. Girls are smarter

than boys.

3. Hermit crabs like

colorful shells.

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Experiment

A procedure to test the

hypothesis.

You figure out a way to

test whether the

hypothesis is correct or

not.

The outcome must be

measurable(quantifiable)

Record and analyze

data.

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Controls and Variables

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Scientific Experiments Follow Rules

An experimenter

changes one

factor and

observes or

measures what

happens.

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.

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What is the Purpose of a

Control?

Controls are NOT being tested

Controls are used for COMPARISON

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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.

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Fair Test

It is important for your

experiment to be a fair

test.

A "fair test" occurs when

you change only one

factor (variable) and

keep all other

conditions the same.

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To be a Valid Experiment:

Two groups are required … the control

experimental groups

There should be only onevariable

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ExperimentExperimental Group -receives some

kind of treatment or condition

Control Group - receives no treatment,

used to compare

** Everything about the two groups,

except the factor you are testing,

must remain exactly the same.

Why?19

Data

Results of the

experiment

May be quantitative

(quantity) or

qualitative (quality)

Must be organized

Can be organized

into charts, tables,

or graphs20

Bar Graphs

Bar graphs

are used to

show a

comparison

of multiple

objects.

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Pie Graph

Pie graphs

are used to

compare

the parts of

a whole.

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Line Graphs

Line graphs

are used to

show the

relationship

between

variables.

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Conclusion

Is the answer to the

hypothesis based

on and justified by

the data obtained

from the research

& experiment

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One more thing… it is

best to make several

trials with each

independent

variable.

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RetestIn order to verify

the results,

experiments must

be retested.

Anyone can get

lucky once!

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In Review …

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

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Example # 1 of experimental design

Hypothesis: If plants

are given Miracle

Grow, then they will

grow taller.

Plants A & B are both

given the same

amount of light,

water,

and are stored at the

same temperature.

Plant A is given Miracle

Grow

All the variables are

kept constant except

the one you are

testing.

Independent Variable - the

factor you change, what you

do to your exp. group.

(Miracle Grow)

Dependent Variable - what

happens as a result of that

treatment, what you are

measuring (height of plant)

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Collecting Data

Data Table Example

A scientist carefully collects and organizes data from the

experiment. Data should always be presented in a neat

fashion, usually tables or graphs.

Data can be powerfully

displayed as a graph

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Alternate Data Collection - what if you grew

hundreds of plants, and exposed half of them

to Miracle Grow. You might choose to measure

all your plants at the end of a week

Height of Plants (cm) Average

Plants in Group A 4 5 4 11 6 6

Plants in Group B

(control)3 4 5 7 6 5

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Conclusions

Based on the data, a scientist then determines whether

the hypothesis was supported or refuted.

Be careful here, scientists usually don't use the word

"prove" because there are no absolutes in science.

In science, every conclusion must assume that the

conclusion is only "true to the best of our knowledge".

This is an important distinction between science and

other subjects.

Science is subject to change when new evidence is

found.

And while experimentation and observations can provide

strong evidence for a conclusion, it is not absolute

proof.

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Fatter Splatter

Which balloon will

make the

biggest splatter?

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Example # 2 of experimental design

Hypothesis

Student’s Statement:

I thought that the closer

to the ground the

balloon was, the bigger

the splatter would be.

The reason I believed

this was because the

balloons closer to the

ground would hit the

ground harder.

“I think the closer

I drop the

balloon to the

ground, then

the bigger the

splatter would

be.”

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Materials

These are the things I needed to do my experiment:

1. BALLOONS - for something to drop

2. WATER - to fill the balloons

3. MEASURING TAPE - to measure the drop height

and the splatter

4. LADDER - for someplace to drop the balloons

from

5. BOWL - to hold the balloons

6. CAMERA - to take picture of the procedure

7. PENCIL AND PAPER - to write down the results

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Variable

The variable for my

experiment was using

different heights to

drop the balloons from.

Using the measuring tape

and a ladder we

dropped the balloons

from 5 different heights.

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The Control

The control for my

experiment was

keeping the size of

the balloons the

same.

We filled up the

balloons with water

and measured them

so they would be 13

inches around.

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Procedure

STEP #1: We filled each

balloon with water.STEP #2: We measured

each balloon so they

would be the same.

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STEP #3: We measured

different heights with the

measuring tape.

We then used 4 ft., 6 ft., 8

ft., 12 ft., and 15 ft.

We dropped one balloon

from each height.

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STEP #4: We measured the

width of the water splatter

for each balloon drop.

STEP #5: We used the

wettest middle part to

measure. Then we

wrote it all down.

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ResultsWe filled new balloons to 13 inches

around.

We dropped the balloon from 4 ft.

and it bounced.

Then we got on the ladder and did

6 ft. and it finally splattered.

We measured the biggest part of

the wet area in the middle.

At 6 ft. the splatter was 48 inches.

At 8 ft. it measured 56 inches.

Then we dropped from my

bedroom window.

At 12 ft. the splatter measured 58

inches.

The last measured 62 inches from

15 ft. high.

We threw the balloons left over at

each other! 40

Conclusion

I was wrong about my hypothesis and I learned

a couple of things.

1. The higher you drop a balloon, the more the

splatter spreads.

2. This is because the balloon has more time to

go faster to hit the ground harder.

3. By accident, I also learned that bigger

balloons splatter more than smaller balloons.

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