Scientific Method
7th grade science
Name: ___________________
Student#:____
Vocabulary
Term
Definition
Control Group
•The group in an experiment in which the
independent variable is not manipulated; it is used to
make comparisons.
Dependent variable
•The factor in an experiment that is measured
•The result; there may be 1 or many.
Hypothesis
Your “prediction” of what you think will happen.
Independent Variable
•The factor in an experiment that you are testing.
•There can only be 1 in a valid experiment.
Variables Held Constant
•Factors that remain the same between the control
and experimental group.
Inference
•A reasonable conclusion based on an observation.
Plant Growth
A student studied the effects
of different colored lights on
plant growth. To do this, she
set up an experiment. She
grew 2 plants under the
conditions shown in the
drawing.
1. She concluded that plants grow better
under red light. Comment on her
conclusion.
2. How could you improve her
experiment? Use the data table to show
the new variables in your redesigned
experiment.
Variables
Plant 1
Plant 2
Light
Red
Blue
Temp
20O C
20O C
Water
1L
1L
Time
2 weeks
Plant
Rose
2 weeks
Rose
Six Steps of the Scientific Method
*People Really Hate Elephants On Cars
P- Problem
R- Research
H- Hypothesis
E- Experiment
O- Observation
C- Conclusion
Six Steps of the Scientific Method
1. Problem- Question you want to answer
2. Research- Info you gather to prepare the experiment
3. Hypothesis- Prediction, what you think will happen in
the experiment
4. Experiment- A procedure used to determine if the
hypothesis is correct
5. Observation- Data collected in the experiment
6. Conclusion- Decide if your hypothesis was supported?
Examples of the six steps
1. Problem- Do mice gain weight if given extra Vitamin C?
2. Research- Learn about mice, vitamin C, their diet, living space needs
3. Hypothesis- If mice are given extra vitamin C, then they will
weigh more.
4. Experiment- 2 groups- 1 group gets normal amount of vitamin
C, 1 group gets twice as much.
5. Observation- Weigh mice after 2 weeks- Vit C mice weigh the
same as non-vit C mice.
6. Conclusion- Hypothesis is not correct.
Variables:
Factors in an experiment
Independent variable:
•The one thing being changed
•Can only be one!
•“The Cause”
Variables Held Constant:
•Factors that are NOT allowed to change.
Dependent variable:
•Data you collect
•Variable you do NOT know at the beginning
•“The Result”
Groups
Experimental Group:
•Has the independent variable altered
Control Group:
•A test run for comparison
•Independent variable not altered
•Group treated “normally”
Hypothesis:
● Prediction
○ What you think will happen in an experiment.
if → then
Written in an ____________________
format.
Ex:
If you turn out all the lights, you will fall asleep faster.
If you eat only fast food, then you will gain weight.
What makes a good hypothesis?
• A good hypothesis can be tested.
• Needs to be a sentence, not a question.
• You’re not guessing what’s correct, it’s based on research
____________
• Use precise language.
Chicken Farmer
A farmer wanted to know if music would make his
chickens lay larger eggs. He took 2 groups of chickens,
and placed one group in a pen with music, the other group
was placed in a pen with no music.
1.What is the independent variable?
2.What is the dependent variable?
3.Which is the control group?
Music
Size of eggs laid
No music
4.List 4 variables that the farmer should hold constant.
Same type of coop
Same age of chicken
Same amount of water
Same type of chicken
More examples of Hypothesis:
•
If a plant receives fertilizer, then it will grow larger.
•
If I put fenders on a bike, then they will keep the rider cleaner.
•
If I study more, then I will receive better grades.
•
If I eat more vegetables, then I will lose weight faster.
•
If I wear a wetsuit, I will be able to swim in cold water longer.
•
If I replace my car battery, then I will get better gas mileage.
Circle the independent variable for each hypothesis.
Underline the dependent variable for each hypothesis.
New Hartford JV Football Team
Scientific Method
Mothers of the football team were tired of cleaning uniforms. They
conducted an investigation of stain removers. They washed 30 filthy
uniforms with Tide. They washed 30 equally filthy uniforms with Gain. They
also washed another load of 30 uniforms without any stain remover. Each
load of laundry was washed in the same washing machine, on the same
cycle, with 1200F water, using equal amounts of soap. The mothers then
looked at the washed uniforms to see how clean they were.
1.Write a hypothesis for the mothers. (Use correct format)
If we use stain remover, then the jerseys will be clean.
2.What is the independent variable?
3.What was the dependent variable?
4.List 2 variables held constant.
Brand of stain remover
How clean the jerseys were
Same washer, cycle, temp
5.What was the purpose of the load without any stain remover?
Control group, for comparison
Zing Candy Bars
A candy called “Zing” was developed.
The developers could not decide on a color
for the wrapper so they conducted a test to
see which color buyers liked best. They
made 8000 (100gram) candy bars and
wrapped 2000 in red wrappers, 2000 in
blue, 2000 in green, and 2000 in brown. All
the bars sold for $.75, had the same shape,
and were placed in the same store display.
The results are in the data to the right.
1.What is the independent variable?
2.What is the dependent variable?
Color of
wrapper
Number sold
Red
1223
Blue
802
Green
1761
Brown
1476
Color of wrapper
# sold
3.What are 4 variables held constant?
Size, shape, price, display
Observations & Inferences
Observations: Using your senses/tools to gather info.
Quantitative Observation: Numerical, often made with a tool.
Ex:
Mr. Arcuri weighs 100kg (muscle)
Qualitative Observation: Description of what is being observed.
Ex: The lightning was bright
Inference: An assumption based on known facts or observations.
Example: you leave the movie theater and see the
rained
ground is wet so you infer that
it ______________.
Read the situation below and determine if the following
statements are observations or inferences.
Situation: You walk into the gym on
Friday morning, the bleachers are
cluttered with paper cups and food
wrappers. The scoreboard is still lit up
and it reads Spartans 47, Visitor 35.
Inference
___________
1. There was basketball game last night.
Observation 2. The score board is lit up.
___________
Inference
___________
3. There were many people there.
Observation
___________ 4. Paper cups are in the bleachers.
Write 5 Observations about the above picture, then right an inference about each observation.
Observations:
Smoke coming from the chimney
1. _____________________________
Inferences about the observations
2. _____________________________
_____________________________
3. _____________________________
_____________________________
4. _____________________________
_____________________________
5. _____________________________
_____________________________
There is a fire in the fireplace
_____________________________
Identify:
1= Qualitative Observations
2= Quantitative
Observations
_____1.
The test tube measures 7cm tall.
2
_____2.
The sulfur smells like rotten eggs.
1
_____3.
The heartbeat of the bird is 190 beats/minute.
2
2
_____4.
The density of water is 1 gram / cm3.
1
_____5.
The book is heavier than the pencil.
2
_____6.
It took 25 minutes for the water to freeze.
1
_____7.
The lemonade tastes sweeter than the iced tea.
Identify:
O = Observation
I = Inference
O
_____8.
You are in a classroom.
I
_____9.
If you study, you will receive an A+ on your science test.
O
_____10.
There is a computer in this room.
I
_____11.
Everyone that has a tattoo likes hard rock music.
I
_____12.
If you become a vegetarian, you will live longer.
Observation or Inference
O 1. The cat is wearing a lime on its head.
____
I
____2.
The cat is going on a motorcycle ride.
I
____3.
The cat like eating limes.
I
____4.
Somebody put a lime on the cat’s head.
O
____5.
The lime is green.
I
____6.
The cat likes wearing the helmet.
I
____7.
The cat is going to take the helmet off.
Look at the drawings of Tom and Joe below. Write “O” if the statement is an
observation and “I” if the statement is an inference.
_____
O 11. Tom is shorter than Joe.
_____
O 12. Joe has straight hair.
O 13. Joe is not smiling.
_____
I 14. Tom is happy.
_____
O 15. Joe has one ear.
_____
I 16. Tom is very energetic.
_____
I
_____ 17. Joe is a good basketball player.
I
_____ 18. Tom likes ice cream.
O
_____ 19. Tom has curly hair.
I
_____ 20. Tom has naturally curly hair.
Tires & Gas Mileage
Scientific Method: Using Data Tables
A tire company tested 4 different tires to
determine what effect they have on gas
mileage. They had 4 identical cars each
drive 1000 miles at 55 mph, with the
same kind of gas. They were all driven
on the same test track under the same
weather conditions. The results are in
the data table.
Type of Tire
Gas Mileage
(mpg)
Firestone
19
Goodyear
20
Continental
17
Michelin
24
1.What was the independent variable in this test?
Type of Tire
Gas Mileage
2.What was the dependent variable?
3.List 5 variables held constant.
Age of tires, type of gas, same track,
distance traveled, speed
4.From this data form a conclusion. Michelin provides the best
gas mileage
Paper Towel Activity
Students compared the soaking power of 1.Place the data in the table below:
Height of water (cm)
5 brands of paper towels. A strip 15cm x
Brand
3cm was cut for each brand. The strips were
4
A
placed into 5 separate beakers. Each beaker
B
1.5
contained 200mL of water. The strips were
C
3
placed in the beakers at the same time and
D
5
to the same depth. After 10 seconds, the
height that the water soaked up the strip was
E
2.5
measured. The following data was collected:
Brand A soaked up 4cm, Brand B soaked up 2. What was the independent variable?
Brand of paper towels
1.5cm, Brand C soaked up 3cm, Brand D
soaked up 5cm, and Brand E soaked up 2.5
3. What was the dependent variable?
cm.
Height of water
4. List 4 variables held constant.
Same beakers, depth, time
span, amount of water
Earthworms: Data tables
Frank conducted a study on
1.Show Frank’s data in a data table.
(Include box letter, soil, # of grams +/-).
earthworms to see what type of soil they
+/- g
Box
Soil
survive in best. He found 5 identical boxes
grams
and placed different types of soil in each
A Clay
+2
box. (Box A-clay, Box B-swamp, Box CB Swamp
+4
sand, Box D-potting soil, and box E had
C Sand
-3
compost.) He then placed a young worm in
D Potting
+1
each box and placed a cover over each
E Compost
+5
box to block out the light and keep the
moisture in. He poured 20mL of water into 2. What is Frank’s problem?
each box daily. At the end of 2 weeks, he Which type of soil do worms grow in best.
3. What is the independent variable?
compared the weights of the worms from
Soil type
start to finish. The following are his results. 4. List 3 variables held constant.
Age of worm, amount of water, time
Box A’s worm gained 2 grams; Box B’s
5.
worm gained 4 grams; Box C’s worm lost 3 Name the dependent variable.
Weight of worms
grams, Box D’s worm gained 1 grams; and
6. What other dependent variables could
Box E’s worm gained 5 grams.
have Frank made?
Length of worm, activity, lifespan
The Mythbusters team uncovers the myth if you talk to your plants
then they will grow better.
The Mythbusters set up 7 different groups of pea plants.
2 groups were exposed to sweet talk talking.
2 groups were exposed to abusive talking.
1 groups were exposed to heavy metal.
1 groups were exposed to classical music.
1 group was exposed to silence.
Identify:
Independent Variable: ________________________________
Dependent Variable(s): ________________________________
2. List as many variables held constant as you can.
a) ________________________________
b) ________________________________
c) ________________________________
d) ________________________________
3. a) Describe the Experimental Group.
b) Describe the Control Group.
4. Mythbusters had a setback. The pea plants turned yellow. Was this a major
setback for the experiment? Why?
5. Why did the Mythbuster team use recordings instead of having people talk to
them?
6. What conclusion did the Mythbusters reach?