The Scientific Method
The Question
• A Scientific Question can be answered by
gathering scientific evidence (with
measurements / observations)
– testable & measurable
– Do not use term – better? How is that measured?
• An example of a scientific question is “Which
freezes faster—fresh water or salt water?”
RESEARCH
“Review of Literature”
Before you can begin your investigation, you must find
out all the information you can that is known about your
topic.
Use
•textbooks and science books
•Science journals (usually high level)
•Internet resources -- (.edu or .gov)
•You must pay attention to the source
•Is the source bias?
•Is the source accurate?
The Hypothesis
• Developing a hypothesis - give possible outcomes
for the tested variables. It is based on research &
previous knowledge and observations.
• MUST be If…Then.
• The “If” states what variables are being tested.
• The “then” part of the hypothesis must be
collectable data.
• An example of a hypothesis is “If fresh water and
salt water are frozen, then the salt water will take
longer to freeze.”
Rationale
• Explain why the hypothesis is correct based on
the review of the literature.
Adding salt to water lowers the freezing point of
water. This will cause salt water to take longer
to freeze.
The Procedure (Experiment)
• The Experiment is a plan to test your hypothesis.
• It should be a detailed, step-by-step list of procedures and should
describe the observations or measurements to be recorded.
• The control, dependent variable, independent variable, and constants need to
be identified.
An example of a procedure:
1. Label two, 500 mL containers with numbers 1 and 2
2. Fill the two 500 mL containers with 300 mL of fresh water
3. Add 10 g of salt in container # 1
4. Place the 2 containers in the freezer
5. Check the containers every 15 minutes and record your
observations.
6. Record the time it took for the water to freeze.
7. Repeat steps 1-6 five times.
Variable(s)
• Variable: Any factor that can change in the
experiment
• Independent Variable: A factor that is manipulated
or changed (on purpose)
• Dependent Variable: Factor that is measured /
observed / or recorded
• Control: The independent variable that is the
“normal” condition
• Constants: variables that are kept the same for all
groups
Let’s Practice Variables
• List all variables that may affect our experiment,
“Which freezes faster—fresh water or salt water?”
Variables that may affect the experiment.
•
•
•
•
•
•
•
Type of water
Amount of water
Temperature of water
Type of salt
Amount of salt
Position in freezer
Type and size of freezer
• Temperature of freezer
• Container used
• How close containers are
to other objects
• How often the freezer
door is opened
Let’s Identify the following:
• Independent Variable
• Control
• Dependent Variable
• Constants
Answers on next slide
Identify the following
Independent Variable: Amount of salt
Control:
Freshwater (zero salt)
Dependent Variable: Time it takes to freeze
Constants:
• Type of water
• Amount of water
• Temperature of water
• Type of salt
• Position in freezer
• Type and size of freezer
• Temperature of freezer
• Container used
• How close containers
are to other objects
• How often the freezer
door is opened
DATA COLLECTION
Data must be collected in a table.
BEFORE experiment is done, you must have a data
table.
Use the header row of the table to list the units, do
not list the units in each box.
Time
Elapses
(min)
0
15
30
45
Freshwater
Saltwater
Interpreting Data
• Interpreting data means analyzing the
information collected during the experiment
looking for patterns or trends (relationships)
• This is best done by organizing your data into
GRAPHS.
The Conclusion
• You need to state whether or not the data
supports or does not support the hypothesis.
• Restate your data (use averages).
The Discussion
Write about what you have learned from the
experiment.
-
why did you get the results you did
evaluate your data
relate research to findings
real-life application of results
possible sources of error
ways to improve your project
ideas of further research
Let’s Practice
Will house plants grow faster if you
make the room warmer?
1. Variables that could affect the results:
2. Independent variable:
3. Dependent Variable:
4. Variables to be kept the same -- aka “Constants”
5. Control
6. Write a hypothesis.
7. Write a rationale.
Possible Answers:
1. Variables that could affect the results:
Temperature, plants, soil type, amount of soil,
containers, water, light, plant food
2. Independent variable:
Temperature the plants are kept
3. Dependent Variable:
Height of plant (growth) (You could also measure
weight as an indicator of growth)
4. Variables to be kept the same: Constants
Same kind of plant, same type and amount of soil,
identical containers, same amount of water, same
amount of light, same amount of food
5. Control: Room Temperature
6. Hypothesis: If house plants are grown in different
room temperatures (15 oC, 25 oC, and 35 oC) then
the plants grown in 35 oC will grow the fastest.
7. Rationale: The temperature affects the rate of
chemical reactions. Because the rate of chemical
reactions increases with temperature, the plant
will grow faster in the higher temperature.
Answer for these two Questions:
Question 1: Does fertilizer make a plant grow taller?
Question 2: Is studying in a quiet place better than
studying in a noisy place?
1. Variables that could affect the results:
2. Independent variable:
3. Dependent Variable:
4. Constants (variables to be kept the same)
5. Control
6. Write a hypothesis.
7. Write a rationale.
Does fertilizer make a plant grow taller?
1. Variables that could affect the results:
2. Independent variable:
3. Dependent Variable:
4. Constants (variables to be kept the same)
5. Control
6. Write a hypothesis.
7. Write a rationale.
Possible Answers: Does fertilizer make a plant grow taller?
1. Variables that could affect the results:
Temperature, plants, soil type, amount of soil, containers,
water, light, plant food
2. Independent variable:
Amount of fertilizer measured in grams
3. Dependent Variable:
Growth of the plant measured by its height in centimeters
4. Variables to be kept the same: Constants
Same kind of plant, same type and amount of soil, identical
containers, same amount of water, same amount of light,
same temperature, same placement of seeds in soil
Possible Answers:
Does fertilizer make a plant grow taller?
5. Control:
No Fertilizer
6. Hypothesis:
If a plant is grown with different amounts of
fertilizers, then the plant that received the most
fertilizer will grow the tallest.
7. Rationale:
Fertilizer provides more nutrients for the plant to
grow.
.
Is studying in a quiet place better than
studying in a noisy place?
1. Variables that could affect the results:
2. Independent variable:
3. Dependent Variable:
4. Constants (variables to be kept the same)
5. Control
6. Write a hypothesis.
7. Write a rationale.
Possible Answers:
Is studying in a quiet place better than studying
in a noisy place?
1. Variables that could affect the results:
participant prior knowledge, age or participant, subject of test,
number and type of questions, type of test (oral / written), time
allowed for test, noise level, directions given…
2. Independent variable:
Quiet study place or a noisy study place
3. Dependent Variable:
Grade on quiz
4. Variables to be kept the same: Constants
Use only 6th grade students, same types of reading (for studying)
and same type of questions on tests, same number of questions,
same time allowed for test, same directions given…
Possible Answers:
Is studying in a quiet place better than studying
in a noisy place?
5. Control:
Quiet place
5. Hypothesis:
If students study for a quiz in a quiet or noisy
environment, then the students that studied in a
quiet environment will get a higher grade on the
quiz.
7. Rationale:
It is easier to concentrate in a quiet area.
Experiment 1
Helen thinks that a special juice will increase the productivity
of workers. She 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, The stacks of stapled papers
is counted. Group A made 1,587 stacks, Group B made
2,113 stacks.
Identify the:
1. Control Group:
2. Independent Variable:
3. Dependent Variable:
4. What should the conclusion be?
5. How could this experiment be improved?
Experiment 2
Bob notices that his shower is covered in a strange green slime.
His friend tells him that coconut juice will get rid of the
green slime. Bob decides to check 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.
Identify the1. What was the initial observation?
2. Control Group:
3. Independent Variable:
4. Dependent Variable:
5. What should the conclusion be?
Experiment 3
Sam 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 the1. Control Group:
2. Independent Variable:
3. Dependent Variable:
4. Does the data support the advertisements claims?
5. How could this experiment be improved?
Making A+ Graphs
S.U.L.T.A.N. C
• S = Scale - numbering axes, spreading out data
• U = Units - What type of numbers are recorded
• L = Labels - What the data is measuring
• T = Title - Scientific and descriptive
• A = Accuracy - Plot points correctly
• N = Neatness - Use a ruler!
• C = Caption
- Explain the graph
Identify the title, label, scale, and units
Does a plant that gets more sunlight
grow faster?
1. Amount of exposure to sunlight measured in hours
2. Growth of the plant measured by its height in
centimeters
3. If plants get different amounts of sunlight, then
the plant with the most sunlight will grow the
tallest.
4. Plants require sunlight for photosynthesis, which
provides the plant with food and energy needed
for growth.