Evolution of Scientific Reasoning

A Very Brief Study

Before there was science…

Prior to the introduction of “science” and “scientific reasoning,” people believed that

gods

control

everything…

Thales

600 BCE

Said all nature is made of water

Rational explanation for physical phenomena.Ex: Earthquakes: earth floats on water and the motion of the water causes the earth to shake!

Other Cool Things Thales Did…

• Used geometry to measure the pyramids, calculate ships’ distance from shore

• Predicted a solar eclipse 585 BCE

• Asked “What is the nature of matter?”

Pythagoras

500 BCE

Said our world is ruled by numbers

Math and physics still use his theorem. Do you know it?

Socrates

400 BCE

First to say that no gods are involved in nature, just logic and rules.

More Fun Facts about Socrates

• Believed knowledge was the true path to goodness.

• Accused of corrupting the youth and “not believing in the gods of the state,” and was sentenced to death.

Plato350 BCE

First to come up with

the theory that “Forms”

or ideas organize

matter so that we can

understand it.

He was Socrates‘s student!

Aristotle

370 BCE

Studied biology, physicsand anatomy using observation and reasoning.

He was Plato’s student!

What You Never Knew about Aristotle

Aristotle became a great teacher.

One of his students was Alexander the Great.

Alexander the Great is Mrs. Macomber’s great-great-great-great-great-great…

grandfather

So don’t make her angry…

Now back to science…

Late Grandpa Alex

Then There Were None

• Shortly after Grandpa Alexander’s death and the burning of the Library at Alexandria, the world entered into the

Dark Ages

• No science was being done, no progress was being made. In fact, science was considered sorcery and that was no bueno.

Glimmer of Hope

• The Middle East did not enter this science-less abyss like Europe did.

• In fact, it is the Muslim scientists that are thought to be the founders of modern Chemistry.

• And that’s where we find this guy…

Jabir ibn Hayyan

770 AD

First practicing alchemist

Knew that the properties of metals could be rearranged to make different kinds of metals.

Fun Facts on Jabir ibn Hayyan

• Alchemical investigations revolved around the goal of producing artificial life.

• Designed and used 20 types of now-common lab equipment.

Meanwhile back at the Ranch…

-- 1348 AD: Europe suffers through the Bubonic Plague

A few [hundred] short years later, they’ve recovered and they’re ready to get down to business!

SCIENTIFIC REVOLUTION!!

Art, science, and math are back at the top!

Welcome Home, Science!

Galileo Galilei

1600 AD

Father of Modern Science

Said that all of the laws of nature are mathematical

The Life and Times of Galilei

Charged as a heretic by the Church for heliocentric (Sun-centered) model of the solar system

Constructed the thermometer.

Isaac Newton

1700 AD

Brought back “Hypothesis” to the scientific process

Did some important stuff with math and physics, too, I think…

And So It Goes

--1937: First placebo trials take place to introduce control groups

--1946: First computer simulation

“Adam”

2009 AD

First “Robot Scientist”

Makes hypotheses,

conducts experiments,

draws conclusions with

no human involvement.

Which Brings Us To…

SCIENTIFIC METHOD!

It’s a way to ask and answer scientific questions by making observations and doing experiments.

What do you want to learn?

What problem do you want to solve?

What is already known about this topic?

Hypothesis – an educated guess

If this, then that.

Follow a step by step procedure. Must be repeatable.

Data: charts or graphsObservations: write about what you seeConclusion: a written summary to

communicate results

Must include WHY your hypothesis was right or wrong.

Was there a mistake or error? Does the experiment need to be repeated?

Experiment Design

• Let’s talk variables!

• Variables are things that can change during an experiment. There are 3 main types…

Independent Variable

• Independent Variable: the one thing you change in an experiment. This is what you’re testing.

• A good experiment has ONLY one independent variable at a time.

Uh, what?• I watched Idiocracy and they watered their

plants with Brawndo: The Thirst Mutilator. That failed miserably for them, but it got me thinking…

• Question: Is there another liquid that would make plants grow better than water?

• Hypothesis: If orange juice is used instead of water, then a plant will grow taller.

OJ vs H2O, Round 1

• Experiment Design: Variables:

• I have decided to test which liquid makes plants grow taller.

• So my independent variable, the thing I’m testing, the thing I’m changing from plant to plant is…..

right, the liquid.

Dependent Variable

• Dependent Variable: the change that happens because of the independent variable

• This is what you measure.

Back to the Juice

• If I give one plant water and one plant orange juice, what result am I going to be measuring?

• In my experiment, plant height is what I measure, and this is my dependent variable.

Last Variable

• Controlled Variable: Everything that you want to remain constant and unchanged.

• Remember good experiments only test one thing at a time. Everything else is a “control.”

My Poor Plants• So while I’m juicing up my plants, here are

some thing I’ll make sure to keep the same between plants:

• The same kind of plant• The same kind of soil• The same location• The same amount of light and heat• The same volume of liquid• I’ll “water” them at the same time.

What else can you add??

Your Turn!

• I’m going to give your group a question.

• Come up with a hypothesis.

• Define independent and dependent variables.

• Come up with at least 10 controlled variables for your experiment.

Last Little Bit

• There are 2 main ways that independent and dependent variables are related to each other.– Directly Proportional– Inversely Proportional

When We Graph This Stuff

Directly Proportional

• As the independent variable increases, the dependent variable increases.

What are some other examples of things that are directly proportional??

Inversely Proportional

• As the independent variable increases, the dependent variable decreases.

What are some other examples of things that are inversely proportional??

Review

• Here are some questions about Scientific Method and scientific reasoning pilled from EOC Review.

• So on May 4th, you will see things like this…

• A student sets up an experiment to investigate the effect of temperature on the volume of 50g of gas inside a balloon. Which statement correctly describes the design of the experiment?

a. The temperature is an experimental control, and the volume is the independent variable.

b. The volume is an experimental control and the temperature is the dependent variable.

c. The mass of the gas is an experimental control, and the temperature is the independent variable.

d. The temperature is an experimental control, and the mass of the gas is the dependent variable.

Always 50g = control

What I change = independent

What I’m testing = dependent

• Scientist Henri Becquerel observed that some minerals, such as potassium uranyl sulfate, could release energy when placed on a photographic plate wrapped in black paper. Becquerel concluded that the potassium uranyl sulfate absorbed energy from the sun and then released energy to expose the photographic plate. Later Becquerel proposed an alternate explanation for the same experiment: the uranium in potassium uranyl sulfate released energy without energy being absorbed from external sources.

• Which statement best explains why Becquerel’s later explanation was more likely to be accurate?

a. Becquerel was considered the best scientific thinker of his time.

b. Becquerel’s peers reasoned that his explanation was scientifically sound.

c. Experiments showed that a sample of uranium could expose a photographic plate even if it was kept in the dark.

d. Scientists were unable to determine the mechanism by which uranium could absorb and release solar energy.

Even the best ones are wrong sometimes.

Doesn’t matter what other people think.

That can’t prove or disprove anything…

• Two measuring tools are shown.

• Which is the most appropriate for measuring 30.0mL of a sodium chloride solution?

a. The beaker because it is more stable and the liquid is less likely to spill.

b. The beaker because it is calibrated to hold large amounts of liquid.

c. The graduated cylinder because it is calibrated to measure the liquid more precisely.

d. The graduated cylinder because it will be nearly filled with liquid.

That’s why we’re careful in lab.

Doesn’t matter how much it will hold.

Doesn’t matter how much it will hold.

We need it to be CORRECT!!

• A company wanted to begin manufacturing and promoting floor cleaner that it claimed would clean floors better than previous products. The company sent its product to two independent research groups, which determined the floor cleaner did clean floors better than previous products. How did the research company come to a bias-free conclusion?

a.Each test was repeated multiple times until the desired results were obtained.

b.Both research groups came to the same conclusion when reviewing the company’s claim.

c. Both research groups used standard protocols made available for the tests.

d.Technicians at each research group did not know which products they were testing and comparing.

BAD science!!

Knowing what it should be affects how hard you try to be “right.”

What you’re supposed to do…

Can’t cheat if you don’t know which one you have!!

• Scientists built a prototype of an electric device that may help predict human reactions to new medicines. Which next step should the scientists take to determine whether the device will be useful?

a. Test the device

b. Modify the device

c. Reevaluate the design of the device

d. Build the real device for application

Yes, let’s make sure it works

Should see how it works first…

Should see how it works first…

Should make sure it works first…

• Air pollution from automobile exhaust is minimized by using electric cars powered by lead-acid batteries. What will be the negative effect of using lead-acid batteries?

a. Toxic metal in the batteries will enter the environment.

b. Sulfuric acid in the batteries will generate electricity.

c. Oxygen and hydrogen will be produced by the batteries.

d. Dense and malleable metal will be used in the batteries.

Electricity is good…

Not bad for the environment…

So is gold, and no one complains about that…

Toxic is bad. Very bad.

The End

• Next time we’re going to discuss data!– Charts, graphs, observations, etc.

• “Lab” Wed/Thurs. The only one ever where you can wear shorts!