1. Experimental Design Terms
What are the things that a good scientific experiment includes?

2. Variables
Something that can vary or change in an experiment

3. What are the variables?
The time it takes to run a kilometer depends on the amount of daily exercise a person gets.
The high the temperature, the faster an egg will cook.
An investigation was conducted to see if keeping the lights on for different amounts of time affected the number of eggs that chickens laid.

4. Types of Variables
Independent – changed by the experimenter (aka manipulated variable)
Dependent – changes because of the independent variable (aka responding variable)
Constants – things that stay the same in the experiment

5. Which is independent & dependent variable?
The water temperature of water rises after calcium chloride is added
The amount of pollution produced by cars was measured for cars using gasoline containing different amounts of lead.
Lemon trees receiving the most water produce the largest lemons.
The amount of algae growth in lakes seems to be directly related to the number of bags of phosphate fertilizer sold by local merchants.
An investigation was performed to see if coen seeds would sprout at different times depending on the room temperature of the water in which they were placed.

6. Now you practice!!!!
Identifying variables worksheet

7. Writing a good hypothesis
What is a hypothesis?
A tentative or trial solution to the question (must be testable)
We will use an If…/then… statement
Identify the IV and DV and plug them in.
Make sure you predict what will happen to the variables
Example: If the amount of lead in gasoline increases, then the amount of pollution increases.

8. Now you practice!
Use the margin at the bottom of the identifying variables and write 5 hypothesis using the If…../then… format.

9. Control
Part of the experiment that serves as the standard of comparison
Necessary to detect the effects of hidden variables
Hint: Try to leave out the independent variable
Examples: Have unleaded gasoline in the previous experiment, not watering a plant

10. Repeated trials
Reduce the possibility of chance or random errors during and experiment.

11. How can this experiment be improved?
Most of the time students forget
A control group
Don’t have enough trials