What is Science?

• What is science? – Science is not shaped by the opinions of people. – Science is not a democracy of ideas, but a

competitive arena for seeking solutions to challenging problems.

– It is driven by skepticism, empiricism, and logic.– Only applies to the natural world, if it can’t be

tested then it can’t be science!

• Do you like science? Why or why not?– Science is not just a subject taught in school – Science is a way to understand the world.

• What are the steps in the scientific process?– There are no set steps in the scientific process.– Observe a phenomena– Research and predict why or how it happens– Experiment to collect data (Observations)– Analyze data (Information gathered)– Adjust experimental procedure

or make inferences (logical interpretations of data)

• What is a scientific theory? Give an example.– Explanation for why an event occurs in the natural

world– Calculations and formulas that explain events in

our world– Gravity is the force that causes two particles to

pull towards each other.– A theory can never become a law

• What is a scientific law? Give an example. – A descriptive generalization about how some aspect

of the natural world behaves under stated circumstances.

– Does not explain “why”– All objects dropped on Earth’s surface fall at 32.2 ft/s2

– If acted upon by the environment, the characteristics of a population of organisms will change over time.

– A theory can never become a law

• What is the difference between astronomy and astrology? – Astronomy- the study of celestial objects (such as

stars, planets, comets, etc.) and phenomena that originate outside the Earth’s atmosphere.

– Astrology- a group of systems, traditions, and beliefs which hold that the relative positions of celestial bodies and related details can provide information about personality, human affairs and other matters.

• What is evolution? – Evolution is the change in the inherited traits of a

population of organisms through successive generations.

– If acted upon by the environment, the characteristics of a population of organisms will change over time.

– Explains that species change over time, NOT WHY

• Why is evolution called a theory? – Evolution states that species change over time

when acted upon by a changed environment = Law

– Natural selection states that genetically heritable traits become more or less common in a population over successive generations based on whether the trait is beneficial to the species.

= Theory

Theory, Law, or Observation• If you take a species, divide into two groups, and

place them in two different environments, two separate species will form.

- Observation• Natural selection states that characteristics which

help a species survive in an environment will become more common while characteristics that do not help it survive become less common.

- Theory

• Species change over time when acted upon by the environment.

- Law

• What is a hypothesis?– A tentative statement that proposes a possible

explanation to some phenomenon or event.– Has been researched– Is testable– Has only one aspect that is being tested

(Controlled experiment)

Hypothesis or Rubbish• Whenever my computer glitches, it is because an

Invisible Pink Unicorn has messed with it.• If skin cancer is related to ultraviolet light, then

people with a high exposure to UV light will have a higher frequency of skin cancer.

• If I play the lottery, then I will get rich.• If leaf color change is related to temperature ,

then exposing plants to low temperatures will result in changes in leaf color.

• Salt in soil may affect plant growth.

Testing a Hypothesis

• Independent/Manipulated Variable– the one you, the scientist, control

• Dependent/Responding Variable– the one that you observe and measure the results.

• If skin cancer is related to ultraviolet light , then people with a high exposure to UV light will have a higher frequency of skin cancer.

• If skin cancer is related to ultraviolet light , then people with a high exposure to UV light will have a higher frequency of skin cancer.

Dependent VariableIndependent Variable

• If leaf color change is related to temperature , then exposing plants to low temperatures will result in changes in leaf color.

• If leaf color change is related to temperature , then exposing plants to low temperatures will result in changes in leaf color.

Dependent Variable Independent Variable

• Salt in soil may affect plant growth.

• Salt in soil may affect plant growth.

Independent VariableDependent Variable

Practice for Quiz…

Quiz

• Name 3 characteristics of a hypothesis.• Fill in the blank. A law tell _____ an event

occurs while a theory tells _______ the event occurs.

• Give an example of a law and an example of a hypothesis.

• What does it mean to have a controlled experiment?