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🔬 Science · Scientific Reasoning · Lesson 1 of 6 · 4 min

The scientific method: steps, hypotheses, theories and laws

🧪 Every science question on the TEAS assumes you know how scientists move from a question to an answer. Learn the order once and many items become simple.

💡 Key idea

A hypothesis is a testable prediction, a theory explains why, and a law describes what happens.

🧠 The idea

The SCIENTIFIC METHOD is an orderly way to answer a question with evidence. A typical order: make an observation, ask a question, do background research, form a HYPOTHESIS, test it with an experiment, analyze the data, draw a conclusion, and share the results so others can repeat the work. A hypothesis is a testable, falsifiable prediction, often written as "If ..., then ...". It is never proven true by one experiment; data either support it or fail to support it. A THEORY is a broad, well-tested EXPLANATION of why something happens, backed by many lines of evidence (cell theory, germ theory). A scientific LAW DESCRIBES what always happens under given conditions, often as an equation (the law of conservation of mass), but does not explain why. Theories do not "graduate" into laws; they do different jobs.

✏️ Worked example

A nursing student notices that bread in a sealed bag molds faster on the counter than in the refrigerator (observation). She asks, "Does temperature affect how fast mold grows?" (question). She reads that molds are living fungi (research). Hypothesis: "If bread is stored at a warmer temperature, then visible mold will appear sooner." She stores identical slices at 4 °C and 22 °C (experiment), records the day mold appears (data), finds the warm slices molded first (analysis), and concludes the data support her hypothesis. Last step: she reports her method so a classmate can repeat it.

📌 Takeaways

  • Order: observe, question, research, hypothesis, experiment, analyze, conclude, share.
  • A hypothesis must be testable; data support it or fail to support it, never "prove" it.
  • Theory = well-supported explanation (why); law = description of a pattern (what).

✅ Check yourself

Question 1 of 3

Which statement is written as a testable hypothesis?

  1. Some kinds of plants grow faster than other kinds do.
  2. Plants need water to survive.
  3. If plants get more light, then they will grow taller.
  4. Plants are more beautiful in sunlight.
Show the answer and rationale

Answer: C

A hypothesis is a testable prediction linking a cause to a measurable effect, and the if-then statement about light and height can be tested by measuring growth. "More beautiful" is an opinion that cannot be measured, and "plants need water" is a known fact, not a prediction being tested.

Question 2 of 3

Which best describes a scientific theory?

  1. A guess that has not yet been tested
  2. A rule about nature that has been turned into an equation
  3. A well-tested explanation supported by much evidence
  4. A single experiment that proved an idea
Show the answer and rationale

Answer: C

A theory is a broad explanation of why something happens, supported by many tests and lines of evidence. A guess not yet tested is closer to a hypothesis, and a pattern written as an equation describes a law. No single experiment proves an idea.

Question 3 of 3

After analyzing the data, what should a scientist do next?

  1. Form a brand-new research question
  2. Draw a conclusion about the hypothesis
  3. Repeat the background research
  4. Change the data so that it fits the prediction
Show the answer and rationale

Answer: B

Analysis is followed by a conclusion: do the data support the hypothesis or not? New questions may come later, but changing data to fit a prediction is never acceptable, and research comes before the hypothesis, not after analysis.

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