Unit 1:
Scientific Method
Name:
Period:
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Scientific Method of Problem Solving
Anyone who has ever read a mystery novel or seen a
“whodunit” on TV, has seen the scientific method in action. Anyone who
has ever tried to figure out what happens to the refrigerator light when
you close the door, or where that other sock goes after you put it in the
drier, has used the scientific method. The scientific method is not a
mystical, incomprehensible rite that only “polyester plaid” science nerds
use to solve esoteric problems. Instead, it is a logical, organized
mechanism for identifying and researching a problem, and devising a
strategy for solving it.
The scientific method has a few major parts:
Determining the problem or question.
-For this part, you (the researcher) must decide what it is that you will be
studying. This sounds like a simple procedure, but it is actually very
important. It identifies exactly what you wish to learn and it allows you to
focus only on that material.
-Watching things going on around the world and noticing different trends
helps in developing questions about things you observe that you don’t
understand or you want to understand better. You don’t have to be
observant about the typical “science” stuff. For instance, scientific
observations don’t have to be about chemicals or lab rats, they can be
about people, clothes, food, whatever.
-Developing a good question is important because it gives your
experiment direction and lets other people know what question you are
trying to answer in your experiment. It must be clear. A question such as
“How do students learn best?” is not clear because there are too many
different ways to test it. A better question might be, “Do students learn
better before or after eating?” because it only tests one particular thing.
The answer to the question must be able to be measured in some way.
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“Questions” follow-up:
A.
What are two questions you would like to know the answer to?
1.
2.
B. For each question below, decide if it is written in a way that is
specific and measurable. If it’s not, rewrite it on the line provided
so that it’s a better question for finding an answer to.
1.
Why do people smoke?
2.
How does talking to a plant affect a plant’s height?
3.
What happens if you do not eat breakfast?
4.
Will larger or smaller seeds germinate faster?
5.
Do larger or smaller seeds make prettier flowers?
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Identifying variables
A good question needs to identify the variables you will be
investigating. Variables are conditions that could affect the
outcome of an experiment.
For instance, think about all of the different things that might
affect how well a student does on a test. Their amount of sleep,
how long they studied, how well they paid attention in class, if
they’re feeling well, the behavior of the students around them, if
they’re having trouble at home or they don’t like the teacher…all
of these things, and more, could affect how well that student
performs.
It is important to identify the variables in any experiment. You
want to have as few variables as possible when conducting your
experiment, but you will always have three types of variables,
independent, dependent, and constants (also called controlled).
1. Independent/ experimental variable: factor that is chosen
ahead of time by researcher/ factor changed on purpose
2. Dependent variable: factor that is measured in an
experiment/ data filled in when experiment is conducted.
3. Constants or control variables: condition or conditions that
remain the same in an investigation.
You have to have controlled variables so that you can determine
if the independent variable actually caused the result, or if it was
something else. In a perfect world, all of the variables would be
controlled except for the independent and dependent variables,
but that doesn’t happen very often.
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Practice with variables:
A. Develop at least 2 variables for each of the following situations.
1. What variables can affect the number of fish in a lake?
2. What variables can affect the speed of a runner in a 100 meter dash?
B. Identify the independent (experimental), dependent, and
constant variables for each experiment below. Then, write a good
research question for each experiment.
1. Two groups of students were tested to compare their speed working math
problems. Each group was given the same problems. One group used calculators
and the other group computed without calculators.
What is the independent /experimental variable:
What is the dependent variable:
What is a constant variable:
Research question:
2. Students of different ages were given the same puzzle to solve. The assembly time
was measured.
Independent/experimental variable:
Dependent variable:
A constant/controlled variable:
Research question:
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Background research and development of a hypothesis.
-The hypothesis is not a just a random guess to your problem.
Instead, the hypothesis is an Educated Guess.
- In other words, it involves researching the problem and finding out
what other people have learned, and using that information to help
devise an answer. An important aspect of the hypothesis is that it
should answer the original question, and it should be testable!
•A hypothesis is a special kind of prediction that forecasts (predicts)
how changing one thing (the independent variable) will affect the
result (the dependent variable).
•A hypothesis is best written in the “If ___change in IND V_____, then
___change in DEP V____.” format. After the “if” is the part the
scientist will change on purpose (independent variable). After the
“then” is the result of the change (dependent variable).
Here is an example of a hypothesis:
If the temperature of sea water increases, then the amount of salt
that dissolves in the water increases.
For each of the following questions, write a reasonable
hypothesis using the correct format.
Q: How does the color of a surface affect its temperature?
H:
Q:How will batting practice affect a player’s batting average?
H:
Q: How does the depth of the Ashokan Reservior affect its temperature?
H:
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Design and conduct an experiment
•
Design an experiment whose results will either support or
disprove your hypothesis.
•
The details of your experiment should include the materials used
and the steps followed when conducting an investigation (the
procedure). The material list must be complete and the steps to
follow must be understandable so the activity can be repeated.
•
Other researchers should be able to look at your procedure and do
the exact same procedure and get the same results without you
telling them anything or giving them any clues.
•
In your procedure, be sure to include how many trials will be
performed or how many subjects will be involved in the study.
•
Run the experiment that you have so carefully constructed. In this
step, you will be measuring the dependent variable. This
variable is the thing that is being observed or measured.
•
Any pieces of information that you collect regarding the
dependent variable are called DATA.
-
Part of your data should be quantitative and part of your data
should be qualitative:
•
Qualitative data: data in words, for example written observations
of what you saw, smelled, etc. as the experiment was conducted.
•
Quantitative data: number data, for example measurements that
are taken as the experiment is conducted.
•
Data collected using instruments should NEVER be
rounded.
•
Data collected using calculators may need to be rounded.
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Displaying data in tables and graphs
Tables and graphs are a way for people to see the data you have
collected during an experiment and be able to analyze it quickly and
accurately. In tables and graphs, data is arranged in such a way that it
makes it easier for people to see and understand.
Tables
The first column in a table lists the items to be compared: the
independent/experimental variable. Draw the letter I around the
independent variable in the table below.
The first row of the table lists the specific characteristics being
measured: the dependent variable. Draw the letter D around the
dependent variable in the table below.
Each table should have a title to say what type of information the table is
showing. Title should be dependent variable vs. independent variable.
On the lines below, identify the independent and dependent variables in
this experiment and give the table a title.
Independent variable:
Dependent variable:
Title:
Towel Size
Amount of Liquid Absorbed (mL)
(cm2)
Trial 1
Trial 2
Trial 3
150
13.5
14.5
22.5
200
34.5
46.0
25.0
250
45.5
58.0
52.0
Average
Fill in the last column by calculating the average amount of liquid
absorbed by each size towel: average = sum of trials
# of trials
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Graphs
Graphs help your data be seen quickly and easily and it makes it easier to see trends
in the data rather than looking at large sets of numbers. Only graph AVERAGES.
•Line graphs should be used when both x and y axes have #’s on them.
•Bar graphs should be used when the x axis has words on it.
Checklist for a correctly constructed graph:
Does the title describe a relationship between the independent and dependent
variables? NO FLUFFY TITLES!!!
Are the axes labeled correctly? Is the independent variable on the x-axis and the
dependent variable on the y-axis?
Did you give units when appropriate? Always use a unit on the y axis.
Is the number scale correct? Are the numbers in even increments on both the
horizontal and vertical axis? Did you start at zero or the beginning of your data?
Are the dots connected to each other in a line graph either point-to-point or best
fit? Are the bars equally spaced and the same width in a bar graph?
Relationships in Graphs
•
Graphs can show relationships (or no relationship) between variables.
•
The relationship between variables can be direct or inverse:
•
The relationship between variables can be linear or nonlinear.
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Practice Graph:
Construct a graph comparing the size of the towel to the average amount
of liquid absorbed. Remember to include all the items on the checklist.
Towel Size
Amount of Liquid Absorbed (mL)
(cm2)
Trial 1
Trial 2
Trial 3
Average
150
13.5
14.5
22.5
16.8
200
34.5
46.0
25.0
35.2
250
45.5
58.0
52.0
51.8
Does this graph show a direct or inverse relationship between the variables?
Does this graph show a linear or nonlinear relationship between the variables?
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Analyze data and draw a conclusion.
Step 1:State the facts!
•
Here, it is stated directly whether the hypothesis was supported or not
supported by the data.
•
Give the exact numbers (averages only) for the dependent variable
for each version of the independent variable.
•
For example, the 150 cm2 paper towel held an average of 16.8 mL of
liquid, etc.
•
Make a statement explaining the type of relationship you observed:
direct, inverse, linear, nonlinear, no relationship.
•
Describe any trends or patterns you see in the data.
Step 2. Say Why!
•
Why did you see those particular results? Give a reasonable
explanation based on background research/ results of others.
•
What might you have done differently to make it a better experiment?
What are some possible sources of error?
•
What future testing might you do to make your results more
meaningful?
•
How might the results of the experiment be applied to another
situation, especially a real-world situation.
•
Discuss any questions you still have.
Now that you’ve learned all the parts of a scientific experiment, it’s
time to put the information into practice..
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Review Questions
Science with the Simpsons
A. 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:
1.Independent Variable: __________________________________
2.Dependent Variable: __________________________________
3.One way this experiment could be improved _______________________________
___________________________________________________________________
B. Bart believes that mice exposed to radio waves will become extra strong (maybe
he's been reading too much Radioactive Man). He decides to perform this experiment
by placing 10 mice near a radio for 5 hours. 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 radio waved mice were able
to push the block away. 7 out of 10 of the other mice were able to do the same.
Identify the:
1.Independent Variable: __________________________________
2.Dependent Variable: __________________________________
3.Name one controlled variable: _______________________________
Analyzing Graphs:
Identify the:
1. Independent Variable: ___________________________________________
2. Dependent Variable: ____________________________________________
3. Type of relationship(direct/ indirect): __________________________________
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Lab 1: Coin Conundrums
In this lab, you will use a pipette to put drops of water on different size
coins (penny, nickel, and dime). You will keep adding drops until the
water runs off the coin.
VARIABLES:
Decide which of the following phrases belongs on each line:
diameter of coin
size of drop
# of drops of water held
Independent/Experimental Variable:
Dependent Variable:
Constant/Controlled Variable:
Based on the description of the experiment and the variables, write a
testable research question.
QUESTION:
Based on your prior experience with pennies, nickels, and dimes, write a
correctly worded hypothesis for your experiment.
HYPOTHESIS: If the diameter of the coin is
hold
then it will
water. I think this because
Next, get the materials for the experiment and then follow the steps in
the procedure to gather data.
MATERIALS: pipette, penny, nickel, dime, ruler, beaker with water,
paper towel.
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PROCEDURE:
1.
Measure the diameter of the dime to the nearest tenth and record
the value in the data table.
2.
Fill the pipette with water and squeeze drops onto the coin until the
water falls of the dime. Record how many drops the dime held.
3.
Dry the dime and repeat step 2 two more times. Record your
findings.
4.
Average your three trials for a more accurate idea of how many
drops of water a dime will hold. Record the average to the nearest
whole number.
5.
Repeat the steps using the penny and nickel. Record your results.
DATA:
QUANTITATIVE (NUMBERS): Record measurements for area and no. of drops
held.
Diameter of coin vs. number of drops of water held
Type of
Diameter
Coin
(cm)
Number of Drops of Water
Trial 1
Trial 2
Trail 3
Average
Dime
Penny
Nickel
QUALITATIVE (WORDS): Write one observation about something that was
interesting/ unexpected when you were doing the experiment:
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GRAPH:
Use the data on coin diameter and average number of drops held to
construct a line graph below. Label the three points with their x, y
coordinates (x,y).
Checklist for a correctly constructed graph:
Does the title describe a relationship between the independent and dependent
variables? NO FLUFFY TITLES!!!
Are the axes labeled correctly? Is the independent variable on the x-axis and
the dependent variable on the y-axis?
Did you give units when appropriate? Always use a unit on the y axis.
Is the number scale correct? Are the numbers in even increments on both the
horizontal and vertical axis? Did you start at zero or the beginning of your data?
Are the dots connected to each other in a line graph either point-to-point or
best fit? Are the bars equally spaced and the same width in a bar graph?
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CONCLUSION:
Write a conclusion for the experiment.
1. State the facts!
• State whether or not your hypothesis was supported and use average
data to back up your answer. (ex. The average for the dime was 6).
• Make a statement explaining the trends you observed and any
relationship you observed from your graph (direct, indirect, no
relationship, etc.)
2. Say Why!
•Why might you have seen those particular results?
•Identify at least one possible source of error.
•How does this experiment relate to other situations?
•Discuss at least one question you still have or one possibility for future
research related to this experiment.
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Lab 2: Styrofoam Structures
In this lab, you will design an experiment that involves testing how the variables of height
and mass affect the energy transferred to a nail.
First, decide on which experimental/independent variable you want to focus on. You can
pick either:
length of plastic tube
or
size of metal rod.
VARIABLES: Write the variables below and in the correct spaces in the data table on
page 18. Read through the procedure to identify controlled variables.
Independent/Experimental Variable:
Dependent Variable:
# of drops (to get nail into the foam block)
Constant/Controlled Variables (at least 2):
Now, use those variables to write a testable question.
QUESTION(How does…affect…):
Next, write a properly worded hypothesis that describes how you think your independent
variable will affect the dependent variable.
HYPOTHESIS (If…then…):
because
Now you will need to list the materials needed for your experiment, and complete the steps
in your procedure.
MATERIALS:
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PROCEDURE (steps to complete experiment – include 3 trials):
Fill in the blanks to complete the procedure steps for the materials you have decided to
use.
1. Stick the nail straight into the foam block so that the nail head is 2 cm above the
foam.
2. Put the
cm plastic tube over the nail so that the bottom of the
(10 cm/ 20 cm)
tube is on the foam block and hold it firmly in place.
3. Hold the
cm
(5 cm/ 10 cm)
rod over the top of the tube so
(aluminum/ steel)
that its bottom is lined up exactly with the top of the plastic tube.
4. Drop, don’t push, the rod down the tube. Repeat steps 2-4 until the nail is driven
completely into the block.
Record the result in the data table.
5. Repeat steps 1-6 two more times with the same materials and then three times with
the other length plastic tube or metal rod. Calculate averages to nearest whole #.
QUANTITATIVE DATA (NUMBERS):
Title:
vs.
Trial 1
Trial 2
Trail 3
Average
QUALITATIVE DATA (WORDS): Write one observation from the experiment.
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GRAPH:
Use the data from your data table to construct a graph below. Label the
two points with their x, y coordinates (x,y).
Checklist for a correctly constructed graph:
Does the title describe a relationship between the independent and dependent
variables? NO FLUFFY TITLES!!!
Are the axes labeled correctly? Is the independent variable on the x-axis and
the dependent variable on the y-axis?
Did you give units when appropriate? Always use a unit on the y axis.
Is the number scale correct? Are the numbers in even increments on both the
horizontal and vertical axis? Did you start at zero or the beginning of your data?
Are the dots connected to each other in a line graph either point-to-point or
best fit? Are the bars equally spaced and the same width in a bar graph?
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CONCLUSION:
Write a conclusion for the experiment.
1. State the facts!
• State whether or not your hypothesis was supported and use average
data to back up your answer. (ex. Longer tube average was 3).
• Make a statement explaining the trends you observed and any
relationship you observed from your graph (direct, indirect, no
relationship, etc.)
2. Say Why!
•Why might you have seen those particular results?
•Identify at least one possible source of error.
•How does this experiment relate to other situations?
•Discuss at least one question you still have or one possibility for future
research related to this experiment.
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Terms:
1.
observation:
2.
hypothesis:
3.
variable:
4.
independent variable:
5.
dependent variable:
6.
constant/controlled variable:
7. qualitative data:
quantitative data:
8. direct relationship:
9. inverse relationship:
10. experimental group:
11.
control group:
12. theory:
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Important Characteristics for Evaluating Research Studies
Want to be a better consumer of science research? Here’s a short crib sheet for
determining the general legitimacy and generalizability of virtually any study.
What kind of research was it?
Many studies employ an experimental group and a control group. The
experimental group is exposed to the independent variable and the control group is
not. Studies that leave out the control group are usually less useful than those that
have a control group. A survey is the least powerful type of research one can conduct,
as it has no experimental or control group, but can be helpful for identifying trends or
zero in on concepts or hypotheses that can be studied more in-depth.
How big was the study?
A study of less than 50 people in virtually any experimental design is going to have
very, very limited generalizability. This means that while the results may be potentially
interesting, until they are replicated in a larger group, you should take them with a
grain of salt. If the study is about things (not people) there should be a lot of trials.
Who was in the study?
Good research seeks to use participants that are representative of the population in
general. The more representative the sample, the more one can readily generalize
from the results.
How long were people studied for?
A study that examines participants for less than 12 weeks for any type of treatment is
virtually useless. A survey that surveys a group of people at one moment of time
means the results found are good for that specific moment in time.
Who conducted the study?
Generally, most studies that are conducted by universities will exhibit less bias than
those funded by a company (such as a pharmaceutical company) with a direct interest
in achieving a specific result.
How do the authors talk about their results?
Authors should be humble and cautious about their results and not making overlybroad generalizations or summary conclusions (especially about causation). Authors
should also clearly describe the limitations of the current study in any journal article;
articles that leave out such information should be viewed skeptically, as every study
has limitations.
Know the difference between a hypothesis and a theory:
The word theory is often misused in everyday language. Theory and hypothesis are
not synonyms. A scientific theory is a well-substantiated explanation of some aspect
of the natural world, based on a body of facts that have been repeatedly confirmed
through observation and experiment. Such fact-supported theories are not "guesses"
but reliable accounts of the real world.
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Use the checklist on page 22 to evaluate a research study from the
website Science Daily.
1.
What is the topic of the research study?
2.
What are the independent and dependent variables in this study?
Independent:
Dependent:
3.
Identify the control and experimental groups in the study:
Control:
Experimental:
4.
Identify one variable the researchers controlled for in this study?.
5.
How many subjects were involved in the study? Does this make it a good
study?
6.
Who conducted the research?
7.
How long did the study last?
8.
What is the initial conclusion that the researchers came to based on the data
from the study? Cite actual data in your answer.
9.
Identify one additional aspect the researchers would like to study further.
10. What is one other study on the Science Daily website that you find interesting?
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Term Review
Instructions: In the space below or on the lines below,
show that you understand the meaning of 6 of the 12 terms
for this unit. You can do this by writing a story, drawing a
picture(s) with captions, or a bit of both. Just be sure the
terms are underlined and your picture/story shows how the
term is used in context, not just as a definition.
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