Experimental design
–
(The Scientific Method)
With a little Metric System review
and Graphing Strategies thrown in
too…
Warm-up Questions
1.
2.
3.
4.
5.
6.
What is Experimental Design (the ‘Scientific Method’)
and what is it used to accomplish?
What system is used to take measurements in all science
classes?
What is the Base unit used to measure:
•
Length
•
Mass
•
Volume
Name 3 prefixes used in this measurement system and
what the number associated with each.
What Type of graph compares the relationship of two
numbers - a line, bar or pie chart graph?
What type of graph compares the relationship of a
number to a word - a line, bar or pie chart graph?
And the answers are…
1.
2.
3.
4.
5.
6.
The Scientific Method is a logical, consistent
process for stating and solving problems in the
natural world.
The METRIC SYSTEM
Length = meter (m), Mass = gram (g), volume =
liter (l)
Kilo=1000 (103)
Hecto=100 (102)
Deka=10 (101)
deci=1/10 (10-1)
centi=1/100 (10-2)
milli=1/1000 (10-3)
Line Graph
Bar Graph
Warm-up Questions
1.
Can you list 3 components or rules for
writing a great scientific procedure?
2. If you wanted to know how high a
superball would bounce if dropped at
different heights, list one variable being
tested.
3. List one variable you would hold constant
in the superball experiment.
Warm-up Questions
1. What are 3 important parts or components
of a graph?
2. Which axis is the dependent variable?
3. Which axis is the independent variable?
4. What happens if your hypothesis is
incorrect?
Warm-up Questions
Vitamin C Lab!!!
Background information:
Today, we are analyzing sources of vitamins and minerals in our diets. We will investigate which
source of orange juice would have the greatest amount of Vitamin C. (Here: Fresh Squeezed,
Bottled 100% juice, and mix from frozen concentrate)
Research indicates that as long as vitamin C is present, the juice will remain orange when iodine and
cornstarch are added. As soon as the vitamin C is gone, the iodine will react with cornstarch to
change the mixture to dark gray or brown.
Using the following paramenters:
· Test 20 ml of each juice combined with 0.5 g of cornstarch
· T hink about the indication of reaction you are looking for…how will you measure or compare
this between samples?
NOW - Using what you know about the scientific method, complete the following:
Problem:
Hypothesis:
Independent Variable:
Dependent Variable:
Warm-up Questions
What is Experimental design the Scientific Method?
• Experimental
Design is a
logical,
consistent
process for
stating and
solving problems
in the natural
world.
What are the steps to follow?
Generally1. Observe
2. Formulate a Question…Problem
Statement
3. Research or Infer to formulate a
Hypothesis
4. Design a Procedure to test this
hypothesis
5. Experiment and record data
6. Analyze the Results
7. Draw a Conclusion and
communicate the results
The Observation starts it all…
An observation is a
visible or provable fact
or occurrence
VS.
An inference is, “the act of
reasoning from factual
knowledge or evidence.”
This is your opinion drawn
on the observations you
have made.
• Careful observations lead to
questions that arise…
• A Problem Statement is a question
that compares two variables.
– Example: Does the change in the
length of daylight affect the leaf color
of deciduous trees?
What are Variables?
A Variable is anything that changes.
The variables
compared in the
problem statement are
the INDEPENDENT &
DEPENDENT
variables….
*Remember, the
dependent variable
DEPENDS on the
independent variable!!!
Variables
Independent variable
• A variable WE MANIPULATE, or change,
in the experiment.
VS.
Dependent variable
• The Variable that changes as a result of
the independent variable.
• The variable that is measured and
recorded.
What is the difference between a
constant and a control?
• A constant is a variable that does not
change through the entire experiment…a
value that remains the same.
VS.
• The CONTROL is the group or condition
that is used as the basis for comparison
for the results of the changes in the
independent variable
What is a Controlled
Experiment ?
• A Controlled Experiment means that
only ONE independent Variable is being
tested at a time!!!
• This allows the scientists to evaluate the
results of the one thing being tested!!!
Hypothesis Statement
• A hypothesis is the stated outcome
predicted to the problem statement
that will be evaluated by the
experiment…
• This is your expected results or your
“educated guess” to the problem at
hand.
Example: If a superball is dropped from increasing
heights, then the bounce height will also increase
because....
Formatting your Hypothesis
1. If
blah blah blah,
then blah blah blah because…
OR
2. As a statement (3rd person always!!!)
Example: The bounce height of the superball will
increase in direct proportion (this means the
graph of the results will be a straight line with a
constant slope) with the increase in drop height.
Writing a great PROCEDURE!
1.
2.
3.
4.
Written in outline or list
form (step #1 is NEVER
‘Gather all materials’!!!)
This should always be written
in the third person…no
personal pronouns!
IT MUST BE REPEATABLE!
A Clear, Concise List of each
step to follow…this includes
tools used, measurements
taken, location, etc…anything
necessary to exactly
replicate your procedure.
This should include directions
to follow for making and
taking observations over
time!
Collecting DATA
QUALITATIVE
• This is a WORD or
“quality” – a subjective
measure other than an
number…
Examples: An odor, color,
texture, taste, etc.
QUANTITATIVE
• This is a NUMBER or
“quantity” – an
objective measure or
observation…
Examples: Distance, mass,
volume, density
DATA TABLES
1. TITLE that identifies both the IV and DV
2. X Axis – Independent Variable
3. Y Axis – Dependent Variable
4. Calculations are
generally to the
right columns after stated data
Ahh, to GRAPH or not to GRAPH
•
•
Graphs help to communicate and
visualize quantitative (numeric) data.
The most common forms we will use
include:
1. LINE GRAPH
2. BAR GRAPH
3. PIE CHART (rare)
All Graphs will include:
1. TITLE: The Effect of the (IV) on the (DV)...notice that all
words in the title are capitalized except for prepositions.
2. Y-Axis =
DEPENDENT
variable that
4. KEY for
data series
will include:
•Labels
•Unit Measures
•Appropriate
scale to fit the
data
•Consistent
increments
3. X-Axis = INDEPENDENT
variable that will include:
•Labels
•Unit Measures
•Appropriate scale to fit the data
•Consistent increments
This compares a
number to a
number!
This compares a
number to a
WORD!
This displays
percentages or
parts of a whole!
And the
CONCLUSION!
The concluding paragraph (5-8 sentences)
should include the following:
1.
Restate the problem statement.
2. Restate the hypothesis.
3. Accept or reject the hypothesis using the analysis of your data.
Be specific, proving your point with specific data points and
trends.
4. Include a discussion of the validity of your results.
5. How might this experiment be improved or modified to further
test the problem statement.
6. Summarize or restate you conclusion to finish up!
***This must be written in the third person!***
Communication- Sharing of information
is essential to scientific process
Theory
• Supported by
considerable
evidence-never yet
disproven
• Ties together related
hypotheses
Scientific Law
•A Statement of fact
that concisely
explains an action or
group of actions
e.g. Law of Gravity
•Accepted to be true
•Universal
Copyright Cmassengale
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