Investigation Design
What do we call a testable statement that can be supported or refuted by evidence?
A hypothesis
What type of error consistently shifts measurements in one direction, such as a miscalibrated instrument?
Systematic error
Which scientist is widely linked to early experiments on gases and “dephlogisticated air” (oxygen)?
Joseph Priestley
What is the difference between primary and secondary data?
Primary is collected by the investigator; secondary comes from existing sources
What process involves other experts checking scientific methods and conclusions?
Peer review
Name the variable the investigator deliberately changes in a controlled experiment.
Independent variable
What type of error causes random scatter around the true value?
Random error
What did Eratosthenes estimate using geometry and shadow measurements?
Earth’s circumference (accept Earth’s size)
Why should sample size be considered when planning an investigation?
Too small a sample makes results less reliable and more affected by chance
What should a scientific conclusion be linked back to?
The inquiry question or hypothesis and the evidence collected
What are controlled variables, and why are they kept the same?
Factors held constant so only the independent variable explains changes in the dependent variable
How do repeats usually affect the impact of random error on a mean result?
They reduce the effect of random error and improve precision of the mean
How did research on peptic ulcers challenge an earlier accepted explanation?
Evidence supported a bacterial cause rather than only lifestyle or stress
What does it mean if results are reliable but not valid?
Repeats agree, but the method still does not properly answer the inquiry question
Why discuss sources of error in an investigative report?
So readers can judge confidence in the results and how the method could improve
How does choosing an appropriate methodology (experiment, observation, modelling, or secondary research) affect validity?
The method must suit the inquiry question so the investigation actually measures what it claims to measure
Distinguish accuracy from precision.
Accuracy is closeness to the true value; precision is how close repeated measurements are to each other
What does the Doppler effect relate about waves and motion?
Observed frequency/wavelength changes with relative motion of source and observer
How can processed data (tables, graphs, calculations) strengthen an investigative conclusion?
They make patterns clearer and help link evidence to the hypothesis
What is the role of replication in confirming scientific findings?
Independent repeats increase confidence that results are not a one-off or due to error
Why might a real scientific investigation deviate from a simple step-by-step “scientific method” model?
Science often involves iteration, unexpected results, debate, and revised models rather than one fixed sequence
Why must uncertainty be considered before accepting or rejecting a hypothesis?
If uncertainty is large, the data may not reliably support or refute the claim
What can historical investigations teach students about judging scientific integrity?
Methods, evidence, replication, and willingness to revise ideas matter more than following a rigid recipe
Name two ways to improve both the reliability and the usefulness of experimental evidence.
More appropriate repeats/sample size, better controls, reduced systematic error, clearer operational definitions (any two)
List key features of a high-quality investigative report beyond raw results alone.
Clear aim/method, processed data, evaluation of validity/reliability, linked conclusion, and acknowledgements/references