Bell Ringer: Define Qualitative Observation and give an example of one in this room. Define Quantitative Observation and give an example of one in this room Define Inference and give example of inference based upon an observation in this room.

Notes Scientific Method

How Scientists Work: Solving the Problems Much of biology deals with solving problems These problems can be environmental, ecological, health related, etc. No matter what types of problems are being studied, scientists use the same problem-solving steps called… The Scientific Method

Scientific Method Definition A logical and systematic approach or process to problem solving.  Purpose is to answer questions and solve problems http://images.google.com/imgres?imgurl=http://web.syr.edu/~ksegrave/Courses_pages/FieldBiology/FieldBioImages/method.gif&imgrefurl=http://web.syr.edu/~ksegrave/Courses_pages/FieldBiology/Science.html&h=175&w=225&sz=17&hl=en&start=11&um=1&tbnid=wdFWEsauzWqdBM:&tbnh=84&tbnw=108&prev=/images%3Fq%3Dscientific%2Bmethod%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN http://en.wikipedia.org/wiki/Scientific_method

Hypothesis – Possible explanation for a set of observations or possible answer to a question. - Is only useful if it can be tested - May be disproved by a single experiment - “Educated Guess” Theory - Well tested explanation that unifies a broad range of observations - May be revised or replaced

Scientific Method Listing the Steps Make an Observation State Problem Form a testable Hypothesis Design an experiment Collect and Analyze Data Draw Conclusions Communicate Results ***If possible, controlled experiments are designed to isolate and test a single variable.

Variables in an Experiment Variables (Definition) - Factors that can be changed Controlled Variables - all the variables that remain constant Manipulated Variable - variable in an experiment that a scientist purposely changes Responding Variable- the outcome or results, factor in an experiment that may change because of the manipulated variable…. what a scientist wants to observe

Experimenting Let’s look at the text book example of the Scientific Method using Françesco Redi’s Experiment on Spontaneous Generation He was trying to disprove the idea of Spontaneous Generation http://hometown.aol.com/ksmith9526/braininjar.gif Francesco Redi (1668)

Stating the Problem Redi’s Problem: People believed that maggots grew out of raw meat. How do new living things come into being? Spontaneous Generation: once a commonly accepted theory Redi wanted to show what caused the appearance of maggots on meat

Belief based on prior observations (inference) If a leaf lands on water it becomes a fish If a bale of hay is left in a barn it produced mice Muddy soil produces frogs Meat hung out in the market is the source of maggots/flies

Belief based on prior observations Redi observed that maggots appeared on meat a few days after flies were on meat No microscope = no way to see eggs But Redi believed that maggots came from eggs that were laid by flies http://www.afpmb.org/pubs/Field_Guide/Images/originals/Fig.%20166.jpg http://ysp.ucdavis.edu/Research06/lius/alotofeggs.JPG http://www.makezine.com/blog/archive/2006/02/make_a_meat_reddening_carbon_m.html http://images.google.com/imgres?imgurl=http://www.fotosearch.com/comp/ITS/ITS223/itf139053.jpg&imgrefurl=http://www.fotosearch.com/ITS223/itf139053/&h=300&w=300&sz=30&hl=en&start=2&um=1&tbnid=6DHrBUo8SEcATM:&tbnh=116&tbnw=116&prev=/images%3Fq%3Dmaggots%2Bon%2Bmeat%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLB,GGLB:1969-53,GGLB:en%26sa%3DN

Forming a Hypothesis Redi’s Hypothesis: Flies produce maggots. How could he test this? Through a controlled experiment http://upload.wikimedia.org/wikipedia/commons/thumb/0/02/Don_francisco_de_quevedo-villegas.jpg/120px-Don_francisco_de_quevedo-villegas.jpg http://www.ifir.edu.ar/~divulgon/diciembre04/imagenes/redi.jpg

Redi’s Controlled Experiment Redi used two groups of jars Jars that contained meat and no cover Jars that contained meat and gauze cover Jars with meat Uncovered jars http://hometown.aol.com/ksmith9526/braininjar.gif Covered jars

Control and Experimental Groups used as a standard of comparison the group containing the factor (variable) that has been changed Control group: Experimental group: (manipulated variable) Two groups of jars Uncovered jars Covered jars

Variables in Redi’s Experiment Controlled Variables: jars, type of meat, location, temperature, time Manipulated Variables: gauze covering that keeps flies away from meat Responding Variable: Maggots?

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

Collect and Record Data observations and measurements made in an experiment Types of Recorded Data Quantitative - observations that involve measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters Qualitative - observations that do not involve numbers, are of a descriptive nature i.e. white maggots covered the meat, leaves were all wilting http://images.google.com/imgres?imgurl=http://www1.istockphoto.com/file_thumbview_approve/310758/2/istockphoto_310758_the_mad_scientist.jpg&imgrefurl=http://www.istockphoto.com/file_closeup/%3Fid%3D310758%26refnum%3D361997%26Lang%3Den&h=367&w=380&sz=49&hl=en&start=27&um=1&tbnid=vejiM3E-VcJ5JM:&tbnh=119&tbnw=123&prev=/images%3Fq%3Dscientist%26start%3D20%26ndsp%3D20%26svnum%3D10%26um%3D1%26hl%3Den%26sa%3DN

Publish Results 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 Redi’s experiment on insects generation

Repeating the Investigation 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!

Scientific Method How Scientists Work Solving the Problems The reason scientific work is called “RE-search” rather than just "search " is because it is an ongoing process that often times changes our view of the natural world. It is subject to modification in light of new evidence and new ways of thinking.