What is Science?-A process that produces a bodyof knowledge about nature.

-Science is concerned with the collection of facts, and especially the interpretation and analysis of those facts.

Science uses the Scientific Method to answer questions about nature.

-The Scientific Method follows very specific steps, and uses a Controlled Experiment to come to a valid conclusion.

A Controlled Experiment is onewhere only one factor is changedat a time.

Control Group: the group not being tested, serves as a comparison

Experimental Group: the group being tested (variable group)

Scientific Method1)Observation/Fundamental

Question2) Interpretation/Background

Research3)Hypothesis4)Experiment/Data Analysis5)Conclusion

Alexander Fleming (1881-1955)-discovered penicillin (antibiotic)by accident.

-used the Scientific Method to check his discovery, and to makesure any ideas were valid.

Fleming was a bacteriologist, meaning hestudied bacteria.

Fleming was working with a bacteria calledStaphylococcus.

Staphylococcus hasbeen shown to cause a great number ofdiseases in man.

-Fleming found mold growing on aPetri dish of bacteria, and saw that the bacteria died around the area where the mold was growing.

Observation!Did the mold cause the bacteria to die off?

Bacterial Cultures with “dead zones”around mold colonies

Fleming then did some checkingto see what kind of mold it wasgrowing on his dish.

Background Research!“If I did an experiment, what would I use?”

Penicillium notatumon an orange

Fruiting bodies of the penicillium mold

Fleming then guessed that the mold was in some way killingthe bacteria.

Hypothesis!“If I put some penicillium on the bacteria, then they will die”.

Fleming proceeded to put the moldon bacterial cultures, and looked to see if the bacteria were killed.

Experimentation!

He kept some bacterial cultures “clean” so he had a comparison

Fleming did not just try the experiment on one petri dish and call it a success.

He replicated both the CONTROL and the EXPERIMENTAL many times.

Replication is key to minimizing variation.

Fleming also treated both the CONTROL and the EXPERIMENTAL in exactly the same manner.

All variation EXCEPT that caused by the desired variable needs to be eliminated, or at least minimized.

Otherwise, what REALLY caused the difference?

Which dish is the experimental, and which is the control?Why?

A B C

Fleming was able to prove that it wasonly the Penicillium mold that caused the bacterial cultures to die.

Conclusion!“Based on my experiments, I canconclude that the Penicillium moldcauses the bacteria to die.”

Kinds of Data: Qualitative: expresses a quality about the observation

EX: Color, texture, smell

Quantitative: Implies some kind of number or measurement

EX: weight, height, temperature