Scientific Scientific MethodMethod

A world-wide system A world-wide system used to help solve used to help solve

problems or explain problems or explain natural occurrences.natural occurrences.

What is involved?What is involved? I. Making I. Making observationsobservations

II. Deciding on a II. Deciding on a problemproblem or purpose to focus on or purpose to focus on

III. Stating a III. Stating a hypothesishypothesis

IV. Testing your hypothesisIV. Testing your hypothesis ( (experimentingexperimenting))

V.V. CollectingCollecting and organizing data ( using and organizing data ( using

tablestables))

VI. VI. Analyzing Analyzing relationships b/w data (using relationships b/w data (using

graphsgraphs))

VII. Drawing VII. Drawing conclusionsconclusions

VIII. VIII. VerifyingVerifying the results the results

STEP 1: Make Your STEP 1: Make Your ObservationsObservations

Just think to yourself, “Just think to yourself, “What types What types of things can be observed?”of things can be observed?” temperature, volume, mass, height, color, temperature, volume, mass, height, color,

texture, taste, size, shape, movement …texture, taste, size, shape, movement …

Remember Remember - Observations are- Observations are:: the most important first step in science the most important first step in science &&

continued throughout scientific studies.continued throughout scientific studies.

Practicing ObservationsPracticing Observations

What types What types of things of things can you can you observe in observe in the picture?the picture?

STEP 2:STEP 2: Deciding the Problem or Deciding the Problem or

PurposePurpose

Ask yourself, “Ask yourself, “What do I want What do I want to know about __________ based to know about __________ based on my observations?”on my observations?”

Write your Write your Problem or Problem or PurposePurpose:: As a statement As a statement oror As a questionAs a question

STEP 3: Making Your STEP 3: Making Your HypothesisHypothesis

What is a hypothesisWhat is a hypothesis??

A statement that gives a possible A statement that gives a possible explanation to your problem. (-an explanation to your problem. (-an educated guess at the solution or what the educated guess at the solution or what the results will be) results will be)

Your Hypothesis should be Your Hypothesis should be testabletestable!! It must be observable &/or measurableIt must be observable &/or measurable

What is What is NOT NOT testable with science?testable with science? opinions, politics, morals, social issues…opinions, politics, morals, social issues… There must also be technology There must also be technology

presentably available to prove it!presentably available to prove it!

Is it a Hypothesis?Is it a Hypothesis?Are the following testable? Why or why not?Are the following testable? Why or why not?

1.1. Fish are happy when they swim.Fish are happy when they swim.

2.2. Plants grow taller when Plants grow taller when

fertilized.fertilized.

3.3. It is wrong to hunt animals.It is wrong to hunt animals.

4.4. There is life in the next universe.There is life in the next universe.

5.5. When a baby cries, he is hungry.When a baby cries, he is hungry.

WritingWriting the Hypothesis the Hypothesis Common formatCommon format (but not always (but not always

necessary):necessary):

If…, then…If…, then… You must You must clearlyclearly state both the state both the::

WHAT you are going to test (independent WHAT you are going to test (independent variable) variable)

WHAT you are going to measure (dependent WHAT you are going to measure (dependent variable). variable).

NOTE:NOTE: A hypothesis will state the A hypothesis will state the causecause and and effecteffect in the experiment, as well as a in the experiment, as well as a prediction of what your results will be.prediction of what your results will be.

Hypothesis ExampleHypothesis Example

EXAMPLE:EXAMPLE: Question:Question: Would salt water effect the Would salt water effect the

growth of growth of my plant?my plant?

Hypothesis:Hypothesis: IfIf I water my plant with salt water, I water my plant with salt water,

thenthen the plant’s growth will the plant’s growth will decrease.decrease. --OR-OR- I think salt water will decrease I think salt water will decrease the growth of my plant.the growth of my plant.

Practicing Writing Practicing Writing Testable HypothesesTestable Hypotheses

DIRECTIONS:DIRECTIONS: Write a testable Write a testable hypothesis for one hypothesis for one problem problem given below:given below:

1.1. Would adding soap to a bubble Would adding soap to a bubble

solution make more bubbles?solution make more bubbles?

2.2. Do cooler temperatures affect Do cooler temperatures affect

how bacteria multiply?how bacteria multiply?

3.3. Will acid rain have an effect on Will acid rain have an effect on

the grass in my yard?the grass in my yard?

STEP 4: Testing Your STEP 4: Testing Your Hypothesis (Experimenting)Hypothesis (Experimenting)

All experiments contain many All experiments contain many VARIABLESVARIABLES::

Constant VariablesConstant Variables

controls (kept the same)controls (kept the same) Changing VariablesChanging Variables

independent vs. dependentindependent vs. dependent

Looking back at the hypothesis you Looking back at the hypothesis you wrote, circle the independent and wrote, circle the independent and underline the dependent variables.underline the dependent variables.

1. controls: brand of soap, water 1. controls: brand of soap, water temperature, agitation (swishing), temperature, agitation (swishing), water qualitywater quality

2. controls: strain of bacteria, initial 2. controls: strain of bacteria, initial amount of bacteria, type and amount amount of bacteria, type and amount of food, environment other than of food, environment other than temperaturetemperature

3. controls: amount of water, type of 3. controls: amount of water, type of grass, season, soilgrass, season, soil

There are 2 groups in your There are 2 groups in your experimentexperiment::

The control and the experimental groups.The control and the experimental groups.

Both groupsBoth groups will have the same will have the same controlscontrols! !

Only in the Only in the experimental group experimental group will will oneone variable be changed from the variable be changed from the control group. control group.

You You CANNOTCANNOT change change oror testtest more more than one variablethan one variable at a time! You at a time! You wouldn’t know which variable caused wouldn’t know which variable caused something to happen!something to happen!

STEP 5: Collecting DataSTEP 5: Collecting Data

Create a table of the data. Create a table of the data. Don’t forget to put units in Don’t forget to put units in the headings and add a the headings and add a specific title.specific title.

Analysis of DataAnalysis of Data

Graphs provide visual comparison of Graphs provide visual comparison of data data

You must make You must make inferencesinferences (logical (logical connections) and connections) and predict trendspredict trends (natural tendencies).(natural tendencies).

STEP 7: Drawing STEP 7: Drawing ConclusionsConclusions

Did your results agree with Did your results agree with your hypothesisyour hypothesis (Is it valid (Is it valid or supported)?or supported)?

We do not say “proven.”We do not say “proven.”

Include Include errorserrors that may that may have been made.have been made.

STEP 8: Verify ResultsSTEP 8: Verify Results Experiments need to be Experiments need to be repeatedrepeated many times to many times to

limit the amount of error or bias.limit the amount of error or bias.

When results are consistent, When results are consistent, THEORIESTHEORIES are are created to explain a range of observations and created to explain a range of observations and findings. findings. EX:EX: Big Bang Theory, Theory of relativity Big Bang Theory, Theory of relativity (Einstein), Cell (Einstein), Cell Theory, Theory of EvolutionTheory, Theory of Evolution

LAWSLAWS, however, are fixed statements of fact , however, are fixed statements of fact that do not explain the “why.” Describes a single that do not explain the “why.” Describes a single action!action!EX:EX: Law of Gravity, Newton’s Laws Law of Gravity, Newton’s Laws

Hypothesis Becomes a Hypothesis Becomes a TheoryTheory

In short, a Hypothesis becomes a In short, a Hypothesis becomes a theory only when many scientists theory only when many scientists test the hypothesis and produce the test the hypothesis and produce the same result.same result.

Once a theory is produced, it must Once a theory is produced, it must also be also be falsifiablefalsifiable, which means it is , which means it is capable of being capable of being modifiedmodified based on based on new evidencenew evidence..