ScienceAccording to the National Academy of Sciences, Science is the use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process.

Phenomena are the events that are observed to happen.

Evidence are observable facts and measurements of the natural world that can be used to evaluate hypotheses, theories, and other scientific explanations.

Scientific Method

How is Science different from other fields of study?

Science uses the scientific inquiry, or the scientific methodDeductive Reasoning- general to specific

reasoning from general theories to account for specific experimental results

(theory-data collection-analysis)

Inductive Reasoning- specific to generalreasoning from specific observations and experiments to more general theories

(data collection-analysis-theory)

Scientific Method

How is Science different from other fields of study?

Science uses scientific inquiry, or the scientific methodDeductive Reasoning- general to specific

reasoning from general theories to account for specific experimental results

(theory-data collection-analysis)

Inductive Reasoning- specific to generalreasoning from specific observations and experiments to more general theories

(data collection-analysis-theory)

Scientific Method

Observations

Question

Formulate Hypothesis

Conduct Experiment to test Hypothesis

Analyze Results

Conclusions

Publish

Observation:

The car won’t start when I turn the ignition.

Question:

Hypothesis:

Test hypothesis:

Analyze Results:

Draw Conclusion:

New hypothesis:

Scientific Method

• Observations– Suggest questions to investigate

• Question– Why does something happen

Research the question

• Hypothesis– A testable explanation for an observation

Scientific Method• Conduct Experiment

– Process of testing a hypothesis or prediction by gathering data under controlled conditions

– Control vs Experimental GroupControl group: a group that has not been exposed

to some factor (variable). It is used to compare the experimental group.

Experimental group: a group that has been exposed to the factor (variable)

Independent variable (IV): the variable you manipulate that you believe will affect the DV

Dependent variable (DV): the outcome variable, i.e., variable you measure

• Collect, organize, analyze data– Determine whether data is reliable– Determine whether data supports or does

not support the hypothesis or prediction– May use statistics

• Compare data from other studies• Determine relationships• Determine experimental error

Scientific Method

• Drawing Conclusions – To understand something not previously

understood– To produce a model

• Construct a representation of an object, a system, or a process to help show relationships given the data

• A model is an explanation supported by data• Use the model to generate new hypotheses or

predictions

Scientific Method

Scientific Method

The last step of the Scientific Method is to publish the work.

Scientist publish their work so that other scientist can replicate their work.

If other scientist can not replicate the work, the conclusions will not be accepted by the scientific community.

Biased sampling: A sampling technique that does not give you a representative sample.

Confounding factors: factors that were not accounted for in the design that may affect the Independent Variable

Method for Reducing Bias: Randomization in sample selection

Replication:This is necessary to estimate the degree of chance variation among samples.

Randomization: Ensures that each subject in a population or each site used for sampling has an equal opportunity of being selected.

Experimental Design

Sample Size: The larger the sample size, the better. A larger sample size tends to give you a closer estimate of the true population mean.

Experimental Design

A theory is a broad powerful explanation of events in the natural world, supported by the results of many experiments.

– Unifying explanations for a broad range of observations

– Based on testing a collection of related hypotheses

– The solid foundation of science– Can be revised given new evidence

Scientific Method- Theory

Contrasting Hypotheses, Theories, and Laws

Contrasting Hypotheses, Theories, and Laws

Scientific HypothesisScientific Hypothesis

A tentative scientific explanation that attempts to answer questions asked about natural phenomena.

A proposed explanation made on the basis of observation, used to begin a scientific experiment

A tentative scientific explanation that attempts to answer questions asked about natural phenomena.

A proposed explanation made on the basis of observation, used to begin a scientific experiment

Hypothesis

• Based on opinion and observation

• Can NOT be proven true

and can only be

supported

• NEVER EVER EVER

can we call them true

Practice• Bart believes that mice exposed to microwaves will become extra strong (maybe he's

been reading too much Radioactive Man). He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food.

• Independent variable (IV):_(The thing that is changed) ____________• ____________________________________________________________• Dependent variable (DV):__(The thing that will be measured)

___________________________________________________________• Constants: _(The things that will kept the same)

___________________________________________________ • Control: ___(The things that will be kept the same

___________________________________________________• Hypothesis:• If… _____________________________________________________• then… ___________________________________________________

Scientific TheoryScientific TheoryA widely accepted, well documented

statement that addresses and explains many independent observations of nature.

A broad, powerful explanation of events in the natural world, supported by the results of many experiments

A widely accepted, well documented statement that addresses and explains many independent observations of nature.

A broad, powerful explanation of events in the natural world, supported by the results of many experiments

Scientific TheoryScientific TheoryA theory explains how nature works1. should be rational and logical2. should be relevant3. should be extensible

A theory explains how nature works1. should be rational and logical2. should be relevant3. should be extensible

Ptolemy (170 A.D.)- geocentric universe, earth centered universe

Copernicus (1500’s)- heliocentric universe; sun centered universenot accepted until 100 years after his death

Galileo (1600’s)- physicist, astronomer, first to usescientific method ; confirmed earth revolved around the sun

Scientific or Natural LawScientific or Natural Law

A description or rule for how nature appears to behave. A law has a small likelihood of being found incorrect.A Scientific Law describes what nature does under certain conditions

Scientific or Natural LawScientific or Natural Law

Mainly found in physics and chemistry.

Mendel’s Law of Inheritance

Newton’s Law of Gravity

First & Second Laws of Thermodynamics

Matter & Energy

Entropy

It’s YOUR turn now

• Work in groups of 4.

• Come up with a problem that a new student at AHS might have.

• Use all the steps of the Scientific Method to find a solution.

• Cycle through the Hypothesis/Experiment loop at least twice.

The Blind Men and the Elephant (Saxe; 1816-1887)

I.It was six men of Indostan

To learn much inclined,Who went to see the elephant

(Though all of them were blind), That each by observationMight satisfy their mind.

II.The First approached the elephant,

And happened to fallAgainst his broad sturdy side,

At once began to bawl:“Bless me!—but the Elephant is very like a wall!”

III.The Second, feeling of the tusk ,Cried, “Ho!—what have we here

So very round and smooth and sharp?To me ‘t is mighty clear

This wonder of an ElephantIs very like a spear!”

IV.The Third approached the animal,

And happening to takeThe squirming trunk within his hands,

Thus boldly up and spake:“I see,” quoth he, “the Elephant

Is very like a snake!”

V.The Fourth reached out his eager hand,

And felt about the knee.“What most this wondrous beast is like

Is might plain’” quoth he;“‘T is clear enough the Elephant

Is very like a tree!”

VI.The Fifth, who chanced to touch the ear,

Said, “E’en the blindest manCan tell what this resembles most;

Deny the fact who can,This marvel of an Elephant

Is very like a fan!”

VII.The Sixth no sooner had begun

About the beast to grope,Than seizing on the swinging tail

That fell within his scope,“I see,” quoth he, “the Elephant

Is very like a rope!”

VIII.And so these men of Indostan

Disputed loud and long,Each with his own opinionExceeding stiff and strong,

Though each was partly in the right,And all were in the wrong!

Moral.

So, oft in these theological wars

The disputants, I ween,

Rail on in utter ignorance

Of what each other mean,

And prate about an elephant

Not one of them has seen!

The Blind Men and the Elephant, Part 2,

I.They talked, those men from Indostan

While standing at the door,Of elephants and how they looked

(This talk was such a bore!),At last they agreed that the knowledge gained

Required something more.

II.Perhaps each one in his own way,

Did learn a bitOf the beast’s elusive mystery,

But just a part of itWith work, they thought, that they might see

The puzzle pieces fit.

III.‘Twas obvious to all of them

For learning to progress,That they must share in what they found—

Jointly sort out the mess.And seek to fully understand

Elephants, more or less.

IV.Some worked alone and some in teams,

In both the field and lab.Models were made: some soft, some hard

Some good, some pretty bad.But when they pooled the useful work,

And truth they made a grab.

V.They checked each other’s methods out,

Some kept, some put asunder.To use the ones which passed the test

Reduced the chance of blunder.Then they’d trust what they had learned

Of elephants’ fine wonders.

VI.They made great strides in what they knew

Of the nature of the beast.Of what and where and how and why

They knew much more at least.For blind men learned how best to learn

And vision soon increased!

Inquiry In your table groups discuss the

following question.

Compare the similarities and differences between a hypothesis, scientific theory and scientific law?