1. The Scientific Method and Experimental Design

2. Essential Questions
How can information be collected, organized, and communicated from scientific experimentation?
How are real-world problems solved with scientific inquiry and experimental design?

3. How did the “By Golly, By Gum” Lab use the Scientific Method?
Let’s follow the steps and see how they relate to our lab.

4. What were the basic steps in our scientific investigation?

5. State the Problem
Does chewing gum affect it’s mass?

6. Form a Hypothesis
If the bubble gum is chewed, then the mass will increase or decrease.

7. Perform the Experiment
We chewed and carefully timed how long each piece was chewed and recorded our results.

8. Reach a Conclusion
At the end of the experiment, our class analyzed our data and made a conclusion based on the information that we collected.

9. Accept of Reject the Hypothesis
We decided whether or not our hypothesis was correct.

10. Planning an Experiment
In order to successfully plan an experiment, an Experimental Design Diagram (EDD) can be created.

11. Experimental Design Diagram (EDD)
A diagram which details the plan for an experiment and includes all of the parts which follow.

12. A Variable
Any factor that can be changed in an experiment. We might have tried the experiment again with a different flavor of gum.

13. Independent Variable (IV)
(This is sometimes called the manipulated variable). It is the factor (variable) that is purposely changed by the experimenter; the factor the experimenter decides to change.
In our experiment, the IV was chewing the gum. It was the thing that we PURPOSELY CHANGED in the experiment.

14. How many independent variables should a good experiment have?
The number of independent variables found in a good experiment is one.

15. Levels of the Independent Variable
These are the changes that are made in the independent variable.
In our experiment the levels of the IV (chewing the gum) were each numbered table . We had seven levels.

16. Control
This is the level of the independent variable chosen as the standard of comparison; this can be decided in one of three ways:

17. Omitting the IV (Independent Variable)
The level at which the IV factor is omitted (0 of the Independent Variable).
In other words, if you added something to test it, you wouldn’t add it for this control. In our experiment, it would have been a table that didn’t chew the gum. This is level of the IV is frequently used in medical testing.

18. Standard
The level suggested by an outside standard (for example, according to package directions) in the case of comparisons.
Our experiment did not have a standard for the chewing gum.

19. Level of Your Choice
The level selected by the experimenter (your choice).
In an experiment you are allowed to choose a level if one is not recommended or can’t be omitted.

20. Repeated Trials
It is the number of times the experiment is done for each level of the independent variable;
In our experiment, it was four. We had four pieces of gum at each of the seven tables in the room.

21. Why do we repeat an experiment?
Repeated trials are done to find average results and so to reduce the effect of errors. The minimum number of repeated trials at each level of the independent variable (IV) is three.

22. Dependent Variable (DV)
It is the factor (variable) that responds to the changes in the independent variable; it is measured, or counted objectively.
In our experiment, it was the mass of the gum at the end of our timed experiment. This is the part of the experiment where your measurements are made and data is recorded.

23. Constants
All factors which remain the same for each repeated trial for all levels of the independent variable.
In our experiment, it was the same type of gum, amount of time the gum was chewed, same triple beam balance, same location, same time of day, and same people chewing each time. Remember, the IV is NOT a constant. It is the only change that should purposely be made in a good experiment.

24. How Might I Organize and Report My Experiment?
One of the ways that an experiment can be reported and organized is by creating an experimental design diagram (EDD).

25. It may look like this: Title: Hypothesis:. Independent Variable:
Levels of
the IV
Repeated
Trials
Dependent Variable:
Constants:

26. In addition to the preceding parts of the experiment, it also includes:

27. The Title
A statement describing an experiment or data table; it may be written in the form: THE EFFECT OF the independent variable (IV) ON THE dependent variable (DV).
In our experiment, it would be “The Effect of the Chewing Gum on the Mass of the Gum.”

28. Hypothesis
An educated guess about the outcome of the experiment which states the relationship between the IV and the DV, written as an “If……, then……” statement. In our experiment, If the gum is chewed, then the mass will increase or decrease.

29. Your Hypothesis Was your hypothesis correct in the “By Golly, By Gum”?
Remember, it’s okay if it isn’t. Being wrong is part of scientific investigation. Thomas Edison tried over 100 different materials before he discovered the filament that was used in the light bulb.

30. Now it’s your turn:
Create an experimental design diagram for the “By Golly, By Gum” lab experience using the data we collected in class.

31. Essential Questions
How can information be collected, organized, and communicated from scientific experimentation?
How are real-world problems solved with scientific inquiry and experimental design?

32. The Scientific Method and Experimental Design