Chapter 1: Nature of Science

Evaluate whether a question or claim is scientific.
Identify parts of an experiment, including:
- Independent variables
- Dependent variables
- Controls
Differentiate between observations and inference.
Explain the tentative nature of science.

Science is a process of discovery to understand the natural world.
Science encompasses both the process of building knowledge and the knowledge itself.
Scientists test ideas by:
- Generating expectations from an idea.
- Making observations to see if those expectations hold true.

Focuses exclusively on the natural world.
- Science does not address supernatural questions.
Science does not deal with moral/ethical questions.
- It explains observations about the natural world.
- Interpretation and application of scientific information are beyond science's scope.
- Science doesn't dictate how to use scientific knowledge.
Relies on testing and ruling out incorrect ideas.
- Science never proves anything to be true.
- It disproves alternative explanations and repeatedly fails to disprove the correct one.
Science is ongoing and tentative.
- It continually refines and expands knowledge, leading to new questions.
- Accepted scientific ideas are reliable due to rigorous testing but can be revised with new evidence.

Science helps us learn about:
- What is in the natural world.
- How the natural world works.
- How the natural world came to be.
It is a path to understanding, not just a collection of facts.

What is the optimum humidity for the growth of the giant puffball fungus (Calvatia gigantea)?
Are birds attracted to other birds of a specific coloration?
What virus causes a certain disease in a population of sheep?
What dose of amoxicillin is optimal for treating pneumonia in an 80 year old?

Science cannot answer moral, spiritual, or supernatural questions.
Examples of questions that cannot be answered using science:
- How mean is the Grinch compared to Santa Claus?
- Where do ghosts live?
- How ethical is it to genetically engineer human embryos?
- What is the effect of fairies on Texan woodland ecosystems?

A scientific question can be answered by using the process of science:
- Testing hypotheses
- Making observations about the natural world
- Designing experiments
Observations and research are important before setting up an experiment.
Use credible sources of information when learning about a topic.

Curiosity and inquiry drive the development of science.
Scientists seek to understand the world and its operation.
Two main pathways of scientific study:
- Descriptive (or discovery) science: observing, exploring, and discovering.
- Hypothesis-based science: begins with a question or problem and a potential testable answer.
The boundary between these two forms is often blurred.
Observations lead to questions, which lead to hypotheses, which are then tested.
Descriptive and hypothesis-based science are in continuous dialogue.

Biologists study the living world by posing questions and seeking science-based responses.
This approach is common to other sciences.
The scientific method was used even in ancient times.
Sir Francis Bacon (1561-1626) documented inductive methods for scientific inquiry.

Hypotheses often ask whether one factor causes or affects an outcome.
A common way to test a causal hypothesis is a controlled experimental design.
Key components:
- Independent variable: the variable the researcher predicts might cause or affect a specific outcome, also called a predictor.
- Dependent variable: the factor the researcher predicts will be affected by the independent variable, also called the outcome.
- Controls: conditions and features that the researcher intentionally holds constant throughout the experiment.
A control often involves a part of the experiment where no independent variable is applied.
Example: Testing if phosphate limits algae growth in freshwater ponds.
- Artificial ponds are filled with water.
- Half are treated with phosphate weekly.
- The other half are treated with a salt not used by algae.
- Independent variable: phosphate (or lack of phosphate).
- Experimental cases: ponds with added phosphate.
- Control ponds: those with inert salt added.
- Adding salt is a control against the possibility that adding extra matter to the pond has an effect.
If treated ponds show lesser algae growth: support for the hypothesis.
If they do not: reject the hypothesis.
Rejecting one hypothesis does not determine the validity of others.

My toaster doesn't toast my bread.
Why doesn't my toaster work?
There is something wrong with the electrical outlet.
If something is wrong with the outlet, my coffeemaker also won't work when plugged into it.
I plug my coffeemaker into the outlet.
My coffeemaker works.

Typically starts with an observation (often a problem to be solved) that leads to a question.
Example: A student finds the classroom too warm.
- Observation and problem: The classroom is too warm.
- Question: "Why is the classroom so warm?"

A hypothesis is a suggested explanation that can be tested.
Multiple hypotheses may be proposed.
Examples:
- "The classroom is warm because no one turned on the air conditioning."
- "The classroom is warm because there is a power failure, and so the air conditioning doesn't work."

Hypotheses can be used to generate predictions.
Example: "If the student turns on the air conditioning, then the classroom will no longer be too warm."

A hypothesis must be testable to ensure its validity.
It should also be falsifiable, meaning it can be disproven by experimental results.
Examples:
- Non-testable hypothesis: "A hypothesis that depends on what a bear thinks is not testable, because it can never be known what a bear thinks."
- Unfalsifiable hypothesis: "Botticelli's Birth of Venus is beautiful."

Researchers conduct experiments to eliminate hypotheses.
A hypothesis can be disproven, or eliminated, but it can never be proven.
Science does not deal in proofs like mathematics.
If an experiment fails to disprove a hypothesis, it supports that explanation.
A better explanation or a more carefully designed experiment may be found later to falsify the hypothesis.

An independent variable (sometimes called a predictor) is the variable that the researcher predicts might cause or affect a specific outcome.
The researcher will systematically vary the independent variable.
The dependent variable (sometimes called the outcome) is the factor that the researcher predicts will be affected by the independent variable.
In a controlled experiment, the researcher attempts to create conditions where the only difference between experimental conditions is the independent variable.
They hold all other conditions and features constant throughout the experiment.
These features that the researcher intentionally holds constant throughout the experiment are controls.