1. What is Critical Thinking?
A precise process of skillfully applying logic & reason to solve real world problems…
This is not only how we solve problems but also how scientists examine the world around them!

2. The Scientific Method
A series of logical steps to follow in order to solve problems--using critical thinking

3. More on the Scientific Method:
Not followed same way every time
Research may be necessary, before writing a hypothesis
A creative experiment must be designed and carried out to test the hypothesis
Data must be collected and analyzed before a conclusion(s) can be made

4. Famous Experiments:
Spontaneous generation = life could arise from non-living forms
Why would anyone believe spontaneous generation?
They could only observe what there eyes could see—no microscopes…

5. Spontaneous Generation (cont.) Redi’s Experiment:
Redi put meat into three separate jars.Jar 1 was left open Jar 2 was covered with netting Jar 3 was sealed from the outside
Biogenesis = life could only come from other life forms
1668: The experiment of Francesco Redi: Redi's Problem Where do maggots come from? Hypothesis: Maggots come from flies. What are the independent and dependent variables??

6. Spontaneous Generation (cont.) Spallanzani’s Experiment:
In the middle 1700’s, Lazzaro Spallanzani continued the work to show spontaneous generation was not possible: Spallanzani's Problem
What causes microbes to form in decaying broth?
Hypothesis: Microbes come from the air. Boiling will kill microorganisms.

7. Spontaneous Generation (cont.) Spallanzani’s Experiment:
Flask-1Left Open,Turned cloudy, Microbes were found
Flask-2 Sealed,Turned cloudy,Microbes were found
Flask-3Boiled and left open Turned cloudy, Microbes were found
Flask-4Boiled and sealed, Did not turn cloudy, Microbes not found