WELCOME TO BIOLOGY LESSON It’s time to study about…

Scientific Method

How do scientists know what they know? Why is the sky blue? Why does it rain? How did people live in the past? How old is the Earth?

The Answer…. Scientist use SCIENTIFIC METHOD to answer questions and solve problems.

The Scientific Method A. Definition B. Steps

A. Definition A common misperception of science is that science defines "truth".  Science does not define truth, but rather it defines a way of thought.  It is investigation process of rational concepts that can be tested using observation and experimentation to answer questions.  This process is called the scientific method

A. Definition The scientific method is the only scientific way accepted to back up a theory or idea. This is the method on which all research projects should be based. The Scientific Method is used by researchers to support or disprove a theory.

B. Steps in the Scientific Method Observation Question Hypothesis Experiment Data Collection Data Analyze Conclusion Report Result

Observations You observe something in the material world, using your senses or machines which are basically extensions of those senses. A scientist notices something in their natural world

Observations An example of an observation might be noticing : salamanders that develop under acid rain conditions show a greater number of   developmental abnormalities Ah…look at this!!!

Questions You ask a question about what you observe. State the problem or question. Example: "Does acid rain affect the development of salamanders?"

Questions The problem should be: Measurable (submits to the scientific method) Clearly and concisely stated If necessary, divided into simpler measurable components

Hypothesis A hypothesis is an educated guess about solving the stated problem/question. You think the suggested solution/answer to the problem/question. Must be testable.

Hypothesis Sometimes written as If…Then… statements Predicts an outcome. A hypothesis is not valid if it cannot be tested somehow Controlled experiments Gathering more data

Hypothesis An example of a hypothesis might be: “Salamanders that develop under acid rain conditions show a greater number of developmental abnormalities than salamanders that develop in unpolluted waters”.

Experiment A procedure to test the hypothesis. You figure out a way to test whether hypothesis is correct.

Variable – factor in the experiment that is being tested

A good or “valid” experiment will only have ONE variable!

Controls and Variables

Scientific Experiments Follow Rules An experimenter changes one factor and observes or measures what happens.

The Control Variable The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome. Those factors are called controlled variables.

What is the Purpose of a Control? Controls are NOT being tested Controls are used for COMPARISON

Other Variables The factor that is changed is known as the independent variable/manipulated variable. The factor that is measured or observed is called the dependent variable/responding variable.

Example of Controls & Variables For example, suppose you want to figure out the fastest route to walk home from school. You will try several different routes and time how long it takes you to get home by each one. Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

What are the Variables in Your Experiment? Varying the route is the independent variable The time it takes is the dependent variable Keeping the same walker throughout makes the walker a control variable.

One more thing… it is best to make several trials with each independent variable.

Valid Experiments

Remember: To be a Valid Experiment: Two groups are required --- the control & experimental groups There should be only one variable

Let’s think about this.… Two groups of Jars with meat Uncovered jars Covered jars Which is the control group? Which is the experimental group? Uncovered jars Covered jars

Redi’s Experiment on Spontaneous Generation OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Manipulated Variables: gauze covering that keeps flies away from meat Uncovered jars Covered jars Several days pass Maggots appear No maggots appear Responding Variable: whether maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur. Controlled Variables: jars, type of meat, location, temperature, time

Data Collection Results of the experiment May be quantitative (numbers) or qualitative

Data Collection 2 Types of Data Quantitative Data- expressed in numbers by counting or measuring i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters. Qualitative Data- are descriptive and involve characteristics and cannot be counted. i.e. white maggots covered the meat, leaves were all wilting Quantitative Data is easier to analyze because it is less objective

Quantitative or Qualitative???

Data Analyze Must be analyzed Always rely on facts not comparisons. Can be organized into charts, tables, or graphs Put your data into word

Conclusion The answer to the hypothesis based on the data obtained from the experiment. Statistics may be used to evaluate data.

Conclusion If a hypothesis is proven to be true over and over it may be called a law or principle. If a hypothesis seems to be true but is unable to be directly tested, it becomes a theory.

Report Result Communication is an essential part of science Scientists report their results in journals, on the internet, or at conferences This allows their experiments to be evaluated and repeated Scientists can build on previous work of other scientists

In order to verify the results, experiments must be retested.

Retest Repeat the experiment! Sometimes results are unexpected. John Needham challenged Redi’s experiment and designed his own to show that spontaneous generation CAN occur under certain circumstances. Lazzaro Spallanzini designed a slightly different experiment to improve on Needham’s work. Repeat the experiment!

Can you put these steps in order? Define the Problem Analyze Data Report Results Make an Observation State the Hypothesis the Problem http://images.google.com/imgres?imgurl=http://www.abcteacher.com/images/cwg3503.gif&imgrefurl=http://www.abcteacher.com/catalog/pages/cwg3503.shtml&h=283&w=295&sz=51&hl=en&start=14&um=1&tbnid=LNucRj8DmvEUbM:&tbnh=110&tbnw=115&prev=/images%3Fq%3Dscientific%2Bmethod%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN Determine Limitations

Steps of Scientific Method in order 1 State the Hypothesis Make an Observation Define the Problem 2 The Problem 3 4 5 6 Analyze Data 7 8 http://images.google.com/imgres?imgurl=http://www.abcteacher.com/images/cwg3503.gif&imgrefurl=http://www.abcteacher.com/catalog/pages/cwg3503.shtml&h=283&w=295&sz=51&hl=en&start=14&um=1&tbnid=LNucRj8DmvEUbM:&tbnh=110&tbnw=115&prev=/images%3Fq%3Dscientific%2Bmethod%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN 9 10 Report Results Determine Limitations

Review Thinking Like a Scientist !!! Look around the classroom and make an observation…!!! Use the Scientific Method to test hypothesis.

Solving a Problem 1) Identify a Problem 2) State Observations about the problem 3) Form a Hypothesis about the problem (if…then…) 4) Design an Experiment to test the hypothesis 5) Collect Data 6) Analyze Data 7) Form a Conclusion 7) Report result

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