Name: ___________________________________________ Period: ______
A Variable W ay to Practice Variables…
Variables are basically something that changes in the experiment. Follow along in this activity and we will practice
identifying variables….both ones that we DO know about and ones that we might not see at first…
A Quick Recap… use your notes to quickly define these three terms…
Hypothesis: _____________________________________________________________
Independent Variable: _____________________________________________________
Dependent Variable: ______________________________________________________
First, let’s make sure you know how to write a hypothesis: Take a look at these questions one might
as and create a hypothesis. Remember your formula!
1)
I wonder if the number of books I read will help me get smarter?
Hypothesis:_________________________________________________________________________________
______________________________________________________________________________________
2)
I wonder what will happen to my plant if I leave it in the closet with no light?
Hypothesis:_________________________________________________________________________________
_______________________________________________________________________________________
3)
I wonder if I watch movies with a lot of swearing in it, I will start swearing more?
Hypothesis:_________________________________________________________________________________
______________________________________________________________________________________
Now, read the following hypotheses and identify the different variables.
1)
2)
3)
If you increase the number of cigarettes you smoke, then you will increase your risk for lung cancer.
a.
Independent : ________________________________________________
b.
Dependent: __________________________________________________
If you increase the amount of blood in the water, then you will increase the number of sharks in the area.
a.
Independent : ________________________________________________
b.
Dependent: __________________________________________________
If you increase the amount of milk you drink, then you will increase the strength of your bones.
a.
Independent : ________________________________________________
b.
Dependent: __________________________________________________
Name: ___________________________________________ Period: ______
4) If you increase the number of hours you spend in practice, then you will increase the number of free throw shots
you will make.
a.
Independent : ________________________________________________
b.
Dependent: __________________________________________________
Final Practice
In this section, you will read about 2 experiments that I am performing. Please help me write a
hypothesis and help me identify the different variables. – independent and dependent.
I am doing a test to see if there is a connection between how long you run and how fast your heart beats. I will be
performing an experiment where a person will run for a 1 minute and I will check their heartbeat. Then they will run for
2 minutes and I will check their heart rate. I will do this up to 6 minutes and see if there is a connection. What do you
think my hypothesis should be? What are my variables?
Hypothesis:___________________________________________________________________________________
____________________________________________________________________________________________
Independent variable: ________________________________________________
Dependent Variable: _________________________________________________
Volleyball season is right around the corner and I think I need to make sure I am healthy and I want to lose some weight.
I keep seeing these commercials for Special K cereal and if you eat it for 2 weeks, you will lose 10 pounds. I want to test
this idea and see if it actually works. I plan on eating whatever I want for the next two weeks and am going to track my
weight every morning. Then I will eat nothing but Special K cereal, milk and water for two weeks and track my weight
in the morning. What do you think my hypothesis should be? What will my variables be?
Hypothesis:___________________________________________________________________________________
____________________________________________________________________________________________
Independent variable: ________________________________________________
Dependent Variable: _________________________________________________
Name: ___________________________________________ Period: ______
PRACTICE PROBLEM:
You want to determine the effects of a certain fertilizer on the growth of orchids grown in a greenhouse. Materials that are available to you include: greenhouse, 100 orchid plants, water, fertilizer, and soil. You want to know if the orchids will grow best with a weak concentration of fertilizer, a medium concentration of fertilizer, or a high concentration of fertilizer. Here’s your hypothesis: “I predict that the orchids will grow best with a
medium concentration of fertilizer.”
Here’s how we will set up the experiment:
Group 1: (25) plants will receive
Group 2: (25) plants will receive
Group 3: (25) plants will receive
Group 4: (25) plants will receive
plain water.
a weak concentration on a fertilizer.
a medium concentration of fertilizer.
a high concentration of fertilizer.
**The plants will be watered daily. Over a period of a month, the plants will be measured to see
which ones grew the tallest.
a) What is the control group in this experiment? ________________________________
b) Which group(s) of plants are the experimental group? ____________________________
Can you think of any “CONSTANTS” in this experiment?
1)_____________________________
3) ____________________________
2)_____________________________
4) ____________________________
Name the “INDEPENDENT” variable in this experiment: ____________________
What is the “DEpendent” variable in this experiment: ______________________
Study the chart below and answer the following questions:
Is your hypothesis “supported” or “rejected in this experiment? Explain.
__________________________________________________________________
_______________________________________________________.
Analysis Questions: Answer these questions on a separate sheet of notebook paper.
Name: ___________________________________________ Period: ______
1.
2.
3.
4.
Why is it important to have a large sample size in any experiment?
Why is it important to repeat the experiment many times?
What is the importance of the control?
Why is it so important that a scientist accurately describes the procedure used in the
experiment?
1. In a “controlled experiment”, why must all of the variables, except one, be kept
constant throughout the experiment?
Final Practice problem:
“ I want to see if drinking a lot of milk will affect how much you eat at dinner. I will gather five people
for my experiment. For three days I will give them two glasses of milk to drink before they eat dinner. I
will serve the same food for those three days and they will eat a the same time every day. After three
days of drinking milk, I will then have the same people eat for three days without drinking milk before
dinner (again, same food, same eating time). I will record how much they ate in the three days that they
drink milk and the three days they DO NOT drink milk and compare my results.”
What is the independent variable? ________________________________________________
What is the dependent variable? _________________________________________________
What are the constants?
1) _________________________________
2) ________________________________
1) ____________________________________
“I want to see how taping my thumbs will affect the time it takes for me to button my shirt. I will test my
classmate. He (or she) will perform three trials buttoning up the same shirt with their thumbs taped to
their palms. Then that same classmate will do three trials where their thumbs are “not” taped to their
palms. I will average the time (in seconds) that it took my classmate to perform each task and record it in
a chart.
What is the independent variable? _______________________________________________
What is the dependent variable? ________________________________________________
What are the constants?
1) ___________________________________ 2) _______________________________
Name: ___________________________________________ Period: ______