Scientific questions and observations

The deliberately changed amount of water is the independent variable. In exams choose the factor that is actively changed.

Viewing from above can cause an incorrect liquid-level reading. In exams read the meniscus at eye level.

The average of repeated comparable measurements reduces the effect of random variation. In exams average only comparable values.

Without the total duration it is unclear how long observations continued. In exams record both interval and total duration.

The time taken for foam to disappear is a clear measurable indicator of stability. In exams choose an operational measure for an abstract property.

A table with clear headings units and time makes data comparison easier. In exams choose complete and structured recording.

Omitting unsuccessful trials prevents the data from representing the true results. In exams understand that all trials should be recorded.

The number of birds can be counted at fixed times so the question is testable. In exams choose clear counts for field studies.

Similar starting size or measuring change in growth makes the comparison fairer. In exams control initial differences.

Similar results obtained independently by different people using the same method indicate reproducibility. In exams identify independent verification.

The data supports only that sugar dissolved faster in hot water in this investigation. In exams keep conclusions within the limits of the data.

A one-millimetre division supports a reading to one decimal place in centimetres. In exams do not report more decimal places than the instrument allows.

Incorrect calibration can shift all readings away from the true temperature. In exams connect calibration with accuracy.

Information about students' habits can be collected through a questionnaire or survey. In exams choose the method according to the question.

A roadside sample may not represent conditions across the whole area. In exams identify sampling bias.

This statement gives a testable prediction linking the independent and dependent variables. In exams identify a clear if-then hypothesis.

An unusual value may result from error or real variation so it must be checked. In exams do not remove an outlier without evidence.

A complete method and description of variables allow the investigation to be repeated. In exams choose a detailed procedure for reproducibility.

Change in height and time make growth rate measurable. In exams replace vague words with numerical data.

Formation of a new solid precipitate can be direct evidence of a new substance. In exams identify clear evidence of change.

Numerical comparison is valid only after conversion to a common unit. In exams standardise units before comparing.

Applying results from one species to all plants is an unjustified generalisation. In exams keep conclusions within the sample limits.

Regular short intervals are suitable for a moderate change such as cooling water. In exams choose intervals according to the rate of change.

Wide spread may reduce confidence in the difference between averages so variability must be examined. In exams do not rely only on the mean.

A scientific investigation moves from a question to a hypothesis then testing data analysis and conclusion. In exams remember the logical sequence.