Introduction to Scientific Method:

REVIEW:Observation and Data

Honors Biology

Ms. Kim

•ObservationObservation: using your 5 senses to collect information

•DataData: scientific information

•InferenceInference: a logical conclusion or assumption based on your observations

Example…• Your cell phone is

ringing in class • What is an observation?

–I hear a ringing sound.

–I see the phone light up.

• What is an inference? –Someone is calling me.

DATADATA2 TYPES:

•Quantitative: includes observations or data that involves numbers (#’s), amounts or quantities

•Qualitative: includes observations that DO NOT involve numbers; Observations or data that is descriptive.

Scientific Method

What are the steps?What are the steps?**(Initial) Observation : use your 5 senses**(Initial) Observation : use your 5 senses

1.1. State the problem or question:State the problem or question: ●What are you trying to solve or

research? 2.2. Form your hypothesisForm your hypothesis::

– an educated or logical prediction to answer your problem question; use your prior knowledge

– Not just a “guess”– IT MUST BE TESTABLE!!!– ““If…then…because” statementIf…then…because” statement

3.3. Plan your experiment:Plan your experiment: ●decide your procedure, control, variables & materials

4.4. Perform your experiment:Perform your experiment: – Collect data (both qualitative and

quantitative) 5.5. Analyze your data (Analyze your data (ResultsResults):):

– Make sense of your data– put it in LINE graphs/charts/table, etc.

6.6. Conclusion:Conclusion: – Sum up your findings (data) – Restate your hypothesis and state whether

it is supported or not supported basedbased on your resultsesults

– CITE your quantitative and/or qualitative data!!! EXPLAIN your numerical data.

– State and EXPLAIN any experimental error(s) (called error analysis)

Hypothesis Example:

• What will happen to Derrick Rose’s shooting points during a Bulls game if he drank Gatorade everyday for 3 months?

• IF Derrick Rose drank Gatorade everyday for 3 months, THEN Derrick Rose will score more shooting points BECAUSE the Gatorade will provide him energy and help his endurance last longer.

A Controlled ExperimentA Controlled Experiment

• ExperimentExperiment = process to collect data

• There are 2 groups in an experiment:

1.1. Experimental (or test) groupExperimental (or test) group

2.2. Control groupControl group

Experimental vs. Control Experimental vs. Control GroupsGroups

Experimental (Test) Experimental (Test) GroupGroup

CoControl Groupntrol Group

• 1 variable (thing) changes or is tested

•Comparison group

•No changes

•“Normal” conditions

Example:Example: HOW WILL FERTILIZER AFFECT PLANT GROWTH?HOW WILL FERTILIZER AFFECT PLANT GROWTH? WITH FERTILIZER WITHOUT FERTILIZERWITH FERTILIZER WITHOUT FERTILIZER

(plants normally don’t have fertilizer)(plants normally don’t have fertilizer)

>>>>ONLY CHANGE (test) >>>>ONLY CHANGE (test) 11 VARIABLE (thing): THE VARIABLE (thing): THE PRESENCE OF FERTILZERPRESENCE OF FERTILZER

Conditions (or Conditions (or standard variablesstandard variables) that NEED to remain) that NEED to remainthe same for a controlled experiment: the same for a controlled experiment:

• AMOUNT OF SUNLIGHT, AMOUNT OF SUNLIGHT, • SOIL, SOIL, • TYPE OF POT, TYPE OF POT, • TEMPERATURE, TEMPERATURE, • SPECIES OF PLANTSPECIES OF PLANT

++++TEST TEST

GROUPGROUP CONTROL CONTROL GROUPGROUP

GOING BACK TO DERRICK ROSE:

• What will happen to Derrick Rose’s shooting points during a Bulls game if he drank Gatorade everyday for 3 months?

• Experimental group: Derrick Rose drinking Gatorade.

• Control group: Derrick Rose not drinking Gatorade.

• A controlled experiment will have 2 different variables:

1.1. Independent variable Independent variable (“If….(“If….then…then…))

2.2. Dependent variable Dependent variable ((If…If…then…)then…)

Independent VariableIndependent Variable Dependent VariableDependent Variable

•The thing (variable) that CHANGESCHANGES in the experiment.

•Ask “What variable changed in the experimental group?

•“WHAT ARE YOU TESTING or CHANGING?” •Goes on x-axis

•The measured outcome in the experiment.

•Ask “What is being measured?”

•Goes on y-axis

Example:Example: HOW WILL FERTILIZER AFFECT PLANT GROWTH?HOW WILL FERTILIZER AFFECT PLANT GROWTH? WITH FERTILIZER WITHOUT FERTILIZERWITH FERTILIZER WITHOUT FERTILIZER

(plants normally don’t have fertilizer)(plants normally don’t have fertilizer)

Independent variable: WHAT ARE YOU Independent variable: WHAT ARE YOU TESTING?TESTING?

»FertilizerFertilizerDependent variable: WHAT ARE YOU Dependent variable: WHAT ARE YOU

MEASURING?MEASURING? »Plant GrowthPlant Growth

++++TEST TEST

GROUPGROUP CONTROL CONTROL GROUPGROUP

GOING BACK TO DERRICK ROSE’S EXAMPLE:

• The independent, or manipulated variable, is (what are you testing?)

• *Ex: The amount of Gatorade Derrick Rose drinks.

• The dependent, or responding variable, is (what are we measuring/what’s the result?).

• *Ex: Shooting points Derrick Rose will score during a game.

X- Axis = Independent variableX- Axis = Independent variable• If time is present, it is If time is present, it is usuallyusually ALWAYS goes ALWAYS goes

on the x-axis (independent variable)on the x-axis (independent variable)Y- Axis = Dependent variableY- Axis = Dependent variable

T.A.I.L.S for graphs• T = Title is present• A = Correctly label x/y-axes (with label & units)• I = Use consistent intervals on axes• L = Label a key (if applicable) • S = Size (BIG graphs/use entire graph paper)

Now let’s practice with Spongebob…• Which people are in the control group? What is the independent

variable? Patty Power Mr. Krabbs wants to make Bikini Bottoms a nicer place to live. He has created a new sauce that he thinks will reduce the production of body gas associated with eating crabby patties from the Krusty Krab. He recruits 100 customers with a history of gas problems. He has 50 of them (Group A) eat crabby patties with the new sauce. The other 50 (Group B) eat crabby patties with sauce that looks just like new sauce but is really just mixture of mayonnaise and food coloring. Both groups were told that they were getting the sauce that would reduce gas production. Two hours after eating the crabby patties, 30 customers in group A reported having fewer gas problems and 8 customers in group B reported having fewer gas problems.

• What is the control group? • What is the independent variable?• What is the dependent variable?

Group B

New SauceAmount of gas

More practice with Spongebob…

• http://sciencespot.net/Media/scimethodconvar.pdf#search='spongebob%20variable%20worksheet’

Additional Information…• Essential to ALL experiments is:

1)Replication!!!• You NEED to consider your number of trials

– Use the EXACT same conditions in EACH trial– Why?

• To determine if the results are consistent this INCREASES our confidence in the resulting data

• BUT…1) A certain amount of variation is NORMAL!

2) Increasing trial # allows us to obtain an AVERAGE RESULT from different trials.

Additional Information…• Essential to ALL experiments is:

2) Sample size– You NEED to consider your sample size

when drawing conclusions

– For example…– You are working with plants and decide to

plant 2 control plants and 2 test plants.

– 1 test plant and 2 control plants die during the experiment

– WHAT HAPPENS NOW?

Additional Information…• Essential to ALL experiments is:

3) Clear procedure– Do NOT use pronouns!– Use “directional” language

• Example:– Place ______ in _____. – Fill 20 ml of water in a 50 ml graduated cylinder

– Someone MUST be able to REPEAT your procedure over and over to produce similar results!!

Theory vs. Hypothesis• Scientists test hypotheses MANY times in

different ways! (i.e.- w/ new research tools, equipment, etc)

• Many “types” of knowing…science-based knowledge based on careful, repeated observations/testable hypotheses.

• THEORY = a well-tested explanation that is supported by A LOT of evidence (data) – Much broader than a hypothesis

Inductive vs. Deductive Reasoning

INDUCTIVE REASONING:

• Derives general principles from specific observations

• Ex: All organisms are made of cells – based on years of findings from biologists

DEDUCTIVE REASONING:

• Reasoning flows from general to specific

• Ex: If all organisms are made of cells, and humans are organisms, then humans are made of cells.