1. Getting Started:
Four students are having a discussion about what to do for the upcoming science fair. This were the questions they proposed:
Julian: Is it more exciting to drive a motorcycle blindfolded or go skydiving?
Melissa: Is Einstein is the greatest scientist ever?
Jason: How do different types of activity affect human heart rate?
Antonella: Why is the sky blue?
Which student is posing a testable question? Explain your choice and why you think the other three questions are not testable. (Write down your answer on a piece of binder paper, with your name and turn it in for XP).

2. Questions, Hypotheses and Variables

3. Testable Question
A testable question is one that can be answered by designing and conducting an experiment.
The answers to a testable question can be observed and measured.

4. Hypothesis Hypothesis- a testable explanation of an observation.
A hypothesis is NOT just an educated guess about what you think will happen. It must be based on research AND be able to be tested!

5. Elements of a Hypothesis
A hypothesis should:
Define the proposed relationship between the variables.
Worded so it can be tested
Make a clear prediction
Be specific

6. Variables & Controls
A variable is anything that changes in a scientific experiment.
The control is what you use to compare the results to in the end of the experiment.

7. There are 2 types of variables:
Independent (also known as manipulated)
Dependent (also known as responding)

8. Independent Variable
Independent Variable: The variable that is intentionally changed in the experiment, such as the temperature of the water in which an effervescent tablet is dissolved.
Cause
a.k.a Manipulated Variable
Graphed on x axis

9. Dependent Variable
Dependent Variable: the variable that responds to the changes in the independent variable. For example, the time it takes for effervescent tablets to dissolve in three different temperatures of water is the dependent variable.
Effect
a.k.a Responding Variable
Graphed on y axis
2 min
1 min
20 sec

10. Independent Variable vs. Dependent Variable
Also Known As:
Manipulated Variable
Responding Variable
Results:
Cause
Effect
On a graph:
X axis
Y axis

11. Controlled variables
Controlled variables (AKA constants) are the things that are kept the same each time one of the trials in the experiment is repeated.
For example, constants could include the amount of water used, the brand of effervescent tablet used, the type of water used, and the fact that the water was not stirred. As many outside factors as possible should be kept constant in an experiment so that the researcher can be sure that any changes that occur do so because of the independent variable.

12. Control Group
The standard against which the researcher compares the results from each treatment group in the experiment.
For example, the control might be the room temperature water, which is about 20° C.
In many cases, there will not be a true control. The researcher could then set one of the groups as the standard and measure the other groups against that standard.

14. Using variables to write a hypothesis
If fertilizer helps grow larger plants, and a plant is given fertilizer,
then it will be larger than a plant that does not receive fertilizer.
States the relationship between the variables
Manipulated variable
Responding variable

15. Let’s identify the variables and correct these hypotheses...
If you spend more time studying, then your grade will improve.
If the temperature of the room is increased, then the bacteria will grow faster.
If people see funny commercials, then they are more likely to purchase a product.
If you spend a lot of time in the sun, then you will increase your risk of skin cancer.

16. Work with a partner to complete your practice sheets.