The Scientific Method

The Scientific Method

An organized way to solve a problem through experimentation & observation.

Start with an Observation

• Example : Listerine seems to be a better mouthwash and it has more antiseptic ingredients

Form a hypothesis

• Make an educated testable guess based on your knowledge.

Example:

Hypothesis :

How will a high antiseptic mouthwash affect bacteria in comparison to other mouthwashes?

Design an Experiment

• Devise a way to test your hypothesis.

Create a

CONTROLLED

experiment.

• A controlled experiment MUST have 2 groups.

CONTROL GROUP: all conditions remain the same

EXPERIMENTAL GROUP: only the condition that you are testing for is changed

ONLY 1 condition is changed!

• Establish the variables for your experiment.

INDEPENDENT VARIABLE: the variable that is changed by the experimenter (X axis for graphing) DEPENDENT VARIABLE: the effect measured due to the change of the independent variable

(Y axis for graphing)

Mouthwash Experiment

Petri dishBacteria grown

from swab

Control Group -no mouthwash

Experimental Group

Listerine

Scope

Wal-Mart brand

Mouthwash Experiment

INDEPENDENT VARIABLE:

DEPENDENT VARIABLE:

Type of Mouthwash

Amount of bacteria killed

Get Results & Analyze Data• Run the experiment & record

the data

Area of Inhibition of bacteria growth

Area of Inhibition for Mouthwash Brands

Control Listerine Scope Wal-Mart

5 min 0 mm 3 mm 2 mm 1 mm

10 min 0 mm 4 mm 3 mm 3 mm

15 min 0 mm 6 mm 5 mm 4 mm

20 min 0 mm 8 mm 6 mm 4 mm

Draw Conclusions

• Determine from the data collected if the hypothesis was correct or incorrect

EX: Listerine did kill more bacteria than the other brands because it had more antiseptic ingredients.