Exercises: The Scientific Methods
Work through each section in order. These questions focus on the nature of science and scientific reasoning.
Warm-Up: What Do You Already Know?
These questions review vocabulary and concepts from middle school science.
Which of the following best describes a hypothesis in science?
What does an experiment test?
In an experiment, what is the variable that the scientist deliberately changes?
Fluency Practice
Apply core scientific method concepts.
A scientist runs an experiment and the results do NOT support the hypothesis. What is the most scientifically appropriate next step?
Which of the following shows scientific inquiry working as a cycle rather than a straight line?
In science, a theory is best described as:
Newton's Second Law states that . Newton's theory of mechanics explains why this relationship holds and connects it to other mechanical phenomena. Which statement correctly describes the relationship between the law and the theory?
A student says: 'Evolution is just a theory, so it might not be true.' What is wrong with this reasoning?
A scientist tests whether fertilizer affects plant height. She grows 20 plants with fertilizer and 20 plants without fertilizer. She uses the same soil, pot size, watering schedule, and light for all plants. What is the role of the 20 plants without fertilizer?
Which of the following claims is scientific (falsifiable)?
Mixed Practice
These problems test the same ideas in different formats.
Which diagram best represents how scientific inquiry works?
A newspaper headline reads: 'Scientists prove global warming theory wrong!' A classmate says, 'See — theories can't be trusted.' What is the best response?
Newton's Law of Gravitation and Newton's Theory of Mechanics both exist. In your own words, explain what distinguishes a scientific law from a scientific theory. Use these two examples to illustrate your answer.
A physicist studies how solar flares affect satellites by analyzing data collected by space probes over 20 years. There is no laboratory involved. Is this valid science?
In 2011, researchers reported that neutrinos traveled faster than light. Other scientists immediately tried to reproduce the result. They could not — the effect turned out to be a hardware error. What does this episode illustrate?
A student investigates whether homeopathic remedies reduce cold duration. She sets up a double-blind trial. Is this claim scientific?
Application Problems
Read each scenario and answer the questions.
Fatima wants to test whether the length of a pendulum affects how fast it swings. She sets up three pendulums with strings of length 10 cm, 20 cm, and 30 cm. She uses the same weight, releases each from the same angle, and counts swings per minute.
What are the independent and dependent variables in Fatima's experiment?
An ecologist studies how road salt affects the survival of salamander eggs. She cannot bring the streams into a lab, so she selects 10 stream sites: 5 near salted roads and 5 far from roads. She measures salt concentration and egg survival rate at each site, keeping all other environmental factors as similar as possible.
Is this a valid scientific study even though it takes place in the field, not a laboratory?
The ecologist wants to reduce the chance that her results are a coincidence. What is the most important step she should take?
A classmate says: "A scientist ran an experiment to test whether eating breakfast improves test scores. The experiment showed no improvement. The scientist's hypothesis was wrong, so the study was a waste of time."
Explain why the classmate is wrong about what makes a scientific study valuable. Use the concept of hypothesis testing in your answer.
Find the Mistake
Each problem shows incorrect reasoning. Identify the error.
A student reads about the theory of plate tectonics and writes: "This is just a theory — geologists don't actually know whether continents move. We should wait until it becomes a law before we trust it."
What errors does this student make about the meaning of 'theory' and 'law'?
A student reads a headline: "New peer-reviewed study shows that vitamin C prevents colds." The student says: "It was peer-reviewed, so it must be true. I'll recommend it to my family."
What is the student's error in reasoning?
Challenge Problem
This is a bonus problem for extra practice.
A friend says: "Astrology is a science — astrologers make predictions about people's personalities based on star positions, and many people say those predictions are accurate."
Using the concept of falsifiability, explain whether astrology is a science and what it would take to make it one.