Hypothesis

What is a hypothesis?

An educated guess or testable statement about how or why something happens in nature, based on observations and existing knowledge.

What does “educated guess” mean in science?

A prediction or idea formed using prior knowledge, observations, and research — not a random guess.

What are the three key parts of an educated guess?

1. Informed — based on facts, observations, or prior knowledge.

2. Logical — makes sense given the evidence.

3. Testable — can be checked through experiments

How is a hypothesis different from a random guess?

A hypothesis is based on evidence, is testable, and clearly stated; a random guess has no evidence, may not be testable, and is often vague.

Give one example of a direct statement hypothesis in biology.

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Why must a hypothesis be specific and measurable?

So the variables and outcomes can be clearly tested and results can be objectively evaluated.

Why is “Plants like music” a bad hypothesis?

It’s too vague, doesn’t define “like,” and isn’t measurable.

What does “biologically relevant” mean in a hypothesis?

It relates directly to biological processes and mechanisms that can be scientifically tested.

Why is prior knowledge important when forming a hypothesis?

It helps make logical predictions based on existing facts and research.

Example — Convert this random guess into a hypothesis: “I think my goldfish swims faster in the morning.”

“If goldfish are fed in the morning, then they will swim faster afterward, because food increases activity.”

Why is measurability important in hypothesis testing?

It allows scientists to collect objective, quantifiable data to confirm or refute the prediction.

How can wording make a hypothesis untestable?

By using vague, subjective, or emotional terms (e.g., “hate,” “like,” “cool”) instead of precise, measurable language.

Give an example of a biology-specific AP-level hypothesis.

“If the pH of a solution decreases below 6, then enzyme X activity will decrease.”

How can a hypothesis guide experimental design?

It determines what variables to test, what data to collect, and what conditions to control.

Rewrite this bad hypothesis into a good one: “If you water plants, they grow.”

“If bean plants are watered with 200 mL daily, they will grow taller than bean plants watered with 50 mL daily.”