scientific method -...
TRANSCRIPT
Scientific Method
The scientific method is a
way to ask and answer
scientific questions by
making observations
and doing experiments.
2
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.
3
4
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.
5
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.
6
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.
7
Hypothesis
Is a suggested solution to the problem / question.
Must be testable
Sometimes written as If…Then… statements
Predicts an outcome
8
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.
9
10
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.
11
Controls and Variables
12
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.
13
What is the Purpose of a
Control?
Controls are NOT being tested
Controls are used for COMPARISON
14
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.
15
16
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.
17
To be a Valid Experiment:
Two groups are required … the control
experimental groups
There should be only onevariable
18
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.
21
Pie Graph
Pie graphs
are used to
compare
the parts of
a whole.
22
Line Graphs
Line graphs
are used to
show the
relationship
between
variables.
23
Conclusion
Is the answer to the
hypothesis based
on and justified by
the data obtained
from the research
& experiment
24
One more thing… it is
best to make several
trials with each
independent
variable.
25
RetestIn order to verify
the results,
experiments must
be retested.
Anyone can get
lucky once!
26
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
27
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)
28
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
29
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
30
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.
31
Fatter Splatter
Which balloon will
make the
biggest splatter?
32
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.”
33
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
34
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.
35
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.
36
Procedure
STEP #1: We filled each
balloon with water.STEP #2: We measured
each balloon so they
would be the same.
37
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.
38
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.
39
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.
41
42
43