The Scientific Method

The Scientific Method

Scientific Method = Separates science from other ways of studying & learning

It is a system of: asking questions, developing a testable explanation, and using the results to explain the natural world

= “organized common sense”, asking & answering questions

Steps of the Scientific MethodObserve the natural world.1. State a specific problem or question

based on observationsobservations of the natural world.

2. Propose a hypothesishypothesis.

Hypothesis = possible explanation

Steps of the Scientific Method3. Design an experiment to test your hypothesis.

4. Analyze Results to find patterns.

5. Draw a Conclusion. *My hypothesis was correct or incorrect.

Notes:• Often the conclusion leads to further

hypotheses.• Results should be repeatable.

Terminology:

Factor Factor = anything that affects an = anything that affects an experiment.experiment.

Control Control = the test group where the variable is not altered.

Variable Variable = the factor that differs among the test groups.

Example:

In the Garden:

Each spring 20 seedlings yield 50-60 tomatoes by fall.

This spring you add some MiracleGro®. This fall’s yield = 100 tomatoes.

Q. Did you prove MiracleGro®

increased your tomato crop?

A. Not Necessarily.

Was weather better for tomatoes?

Were the same seeds planted?

Were there fewer pests?

Other Possible Factors:

Q. How/What could you do to see if it really was the MiracleGro®?

- Divide the Garden into 2 sections

- Add MiracleGro® to only one section

- Observe & Record

Hypothesis

Hypothesis – A plausible explanation or prediction based on observations and previous research.

If __________________, Then ___________________.

Variables

Independent Variable – the factor in an experiment that is altered or changed by the scientist.

Dependent Variable – the factor that is affected, changed, or determined by the independent variable.

Bringing Variables and Hypothesis Together…

If ___________________, Then _____________________.

If I change this… Then this will happen…

If Independent Variable, Then Dependent Variable.

Science & Truth

• Scientific knowledge is changeable.

• The Scientific method supports – not proves.

• New evidence helps change or reject previous conclusions.

Science and TruthTheory = logical explanation for a broad range of observations

Examples?

Germ TheoryTheory of Evolution

Big Bang Theory

Scientific Method & Yellow Fever

What is Yellow Fever?Walter Reed -Carlos Findlay -

Scientific Method: Yellow FeverYellow FeverScience always starts with observations of the world

around us.

Step 1 – Question

Step 2 - Hypothesis

Step 3 - Experiment

Step 4 – Analyze Results

Step 5 – Conclusion

Presenting results is essential for scientific advancement

Make two observations, two inferences, and two predictions about each photo.

• Observation- information gathered using one or more of the five senses.

Observations:•People wearing helmets•Two people in green and white •One person in in black•One person wear stripes•Persons arms out like a T with a football in hand•Persons arms above their head

Inference- an interpretation of one or more observations.

Inferences:•The playier in black scored a touchdown•#81 is tackling the player in black

• Qualitative observation- deals with descriptions that can be observed but not measured

• Examples- Colors, textures, smells, tastes, appearance, beauty, etc.

• Quantitative observation- an observation dealing with numbers that can be measured

• Examples: Length, height, area, volume, weight, speed, time, temperature, humidity, sound levels, cost, members, ages, etc.

Qualitative or Quantitative?

1. Chemical A and chemical B reacted creating bubbles.

2. The chemical reaction released 10 joules of heat into the environment.

3. The beaker contained 10 mL less water that the previous day.

4. The brown rock is heavier than the black rock.5. The bear has a number 3 shaved into its fur.

Communicating ScientificallyBar Graph – Categorical or Discrete DataEssential Items•Scale•Title•X & Y Axis Labels

Average Raptor Count In Hudson County NJ, 2014

Winter Spring Summer Fall

150 800 300 950

Communicating ScientificallyLine Graph – For Continuous DataEssential Items•Scale•X & Y Axis Labels•Title•Legend

*When there is more than one set of data

Birds Spotted Per Hour In Hudson County During Fall Migration, 2013 & 2014

Time 8am 9am 10am 11am

2013 15 20 16 10

2014 10 23 20 15

Communicating Scientifically• Pie Chart – For Data

Showing Parts of a Whole

Essential Items• Title• Labels For Wedges

or Legend

Count of Each Species of Raptor In Hudson County, Spring 2014

Redtail hawk Osprey Bald Eagle Kestrel Total

1200 500 20 1000 2720

44% 18% 1% 37%

What type of Graph?

1. Change in temperature over time.2. Difference in population for Jersey City,

Hoboken, and Weehawken.3. What percentage of each ice-cream flavor is

sold at grocery store.4. Change in pressure as temperature increases.5. Average height per grade level at

Weehawken High School.

Lab Safety - Rules

• Follow all instructions carefully. Use special care when you see the word CAUTION.

• Familiarize yourself with the location of all safety equipment in your classroom. This may include fire extinguishers, fire blankets, sand, an eyewash, and a shower.

• Never eat or drink in the science laboratory.• Never run, push or engage in horseplay or

practical jokes in the laboratory.

Lab Safety – Rules continued• Report all accidents or safety hazards to your teacher

immediately.• Never perform unauthorized experiments. Never work

alone in a laboratory.• Dispose of used chemicals and matches as your

teacher instructs.• Dress properly:

– Push up sleeves above wrist.– No loose fitting clothing– Tie Back hair.– Wear safety goggles when using chemicals, hot liquids, or

fire.– Wear apron or lab coats.

Lab Safety – Rules continued again• Be extra careful when dealing with heat or fire:

– Never leave hot plate, burner, or any other hot object unattended.– Never reach over an exposed flame.– Use tongs or pot holders to handle hot laboratory equipment.– Never allow flammable materials such as alcohol near an open flame.– Never point the mouth of a test tube towards anybody while it is

heating.• Use care working with chemicals:

– Never taste or touch substances in the laboratory without specific instructions.

– Use materials only from containers that are properly labeled.– Never smell anything without specific instructions. Then wave the air

above the substance toward your nose and sniff carefully. Do not inhale the fumes directly.

– Wash your hands after using chemicals.

Lab Safety – Rules continued one more time…

• Use care working with laboratory equipment:– Do not use chipped or cracked glassware.– Do not force glass tubing or thermometers into

stoppers.– Never look directly at ultraviolet lamps, bright

lights, or the sun. Never look at the sun through a telescope. Damage to the eyes can occur without your being aware of it.

• Turn off everything before you leave for a fire drill or other emergency.

Lab Safety

• Fire Blanket

• Fire Extinguisher

• Emergency Shower

• Emergency Eye Wash

Acting Like a Scientist

Sir Isaac Newton

Charles Darwin

Albert Einstein

Madam Curie

Nicholas CopernicusRosalind Franklin

Language of Science

• anemo – wind• atmo – vapor• bronch – windpipe• calor – heat• eco – house• lingu – tongue• photo – light• sci - know

•Anemone•Atmosphere•Bronchitis•Calorie•Ecosystem•Language•Photography•Science

Measuring ScientificallyInternational System of Units (SI Units)Sort of like the metric system…

-This system is used around the world. -Allows scientist to easily compare data.

Measuring Scientifically - Continued

TOOLS•Meter Stick•Balance

– Equal Arm Balance– Triple Beam Balance– Electronic Balance

•Thermometers•Graduated Cylinders

MEASURE•Distance, Area, & Volume•Mass

•Temperature•Volume

Measuring Scientifically Precision Vs. Accuracy Precision –

Consistently getting the same measurement.

Accuracy –Close to the correct amount.

Significant Figures - Numbers that are both precise and accurate.

Measuring Scientifically• HOW PRECISE

CAN I BE?

• You can measure to ½ of the most precise instrument.

Reading a Meniscus

Significant Figures• ALL non-zero numbers

(1,2,3,4,5,6,7,8,9) are ALWAYS significant.

• ALL zeroes between non-zero numbers are ALWAYS significant.

• ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant.

• ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant.

How Many Sig. Figs?

a.23b.203c..230d.230.0e.0.023f.42.0g.500,000h.500,000.0i..00071j..000710

Observing Scientifically

• Dissecting Microscope • Compound Microscope• Electron Microscope