Year 7 · Evaluating evidence and improving methods

Learn the idea

To evaluate is to judge strengths and limitations using reasons. Ask whether the method addresses the original question, whether relevant conditions were comparable, and whether there is enough evidence for the conclusion. A comment such as the experiment was good is not useful until it names the evidence or method feature.

Close readings can still be wrong

Repeatability describes how close repeated results are under the same conditions. Consistency from an appropriate method contributes to reliability: dependable evidence for the question. Accuracy concerns closeness to an accepted reference value. Several identical readings do not prove accuracy: an instrument could have a fixed offset or be stuck. Check a supplied known reference and the method as well as repeating readings.

Link an improvement to a problem

Name a specific weakness and a change that addresses it: read a scale at eye level, use a finer suitable instrument, keep starting conditions alike, or repeat a variable result. A reference check can reveal an offset. Repetition can reveal variation but cannot automatically remove a consistent offset. Error-category labels are not required in this practice.

Extend the investigation carefully

A further scientific question should follow from the limitation or result and specify obtainable evidence. Change the method to answer it without losing relevant controls. More readings of the wrong quantity do not answer the original question. Unexpected data should prompt checking and better questions, not a rewritten record that hides disagreement.

Assess the right question

The supplied question asks how surface type affects distance for the same model car. A record that changes the car for each surface cannot isolate the surface effect. Evaluate whether the evidence answers the named question before deciding that a neat table or a large number of readings makes the conclusion strong.

Check repeated results and references

A supplied length set is 14, 15 and 16 cm. Its mean (total divided by three readings) is 15 cm, the average level. Its range (largest minus smallest) is 2 cm, the spread of these readings. A model probe reads 22 °C when a supplied reference is 20 °C; it is 2 °C above that reference in this check. Repeating the same wrong offset would not remove it. Use a teacher-approved reference check rather than inventing a correction for every instrument.

Describe useful improvements

A clearer start mark, consistent release method, an appropriate measuring range and further supplied repeats can address specific weaknesses. Explain which problem each change targets. Reading a scale at eye level reduces viewing-angle error; taking more readings without fixing the viewpoint does not address that cause.

Ask a worthwhile next question

After comparing surfaces under the same car and start height, a further question could ask whether the pattern persists for a second specified car tested across the same surfaces. Preserve controls within each comparison and record all supplied results. A new question should extend the evidence rather than repeat an unsupported claim.

Common mistake

A smaller range does not establish a more accurate instrument; a reference comparison answers a different question.

A specific improvement

Name the issue—an inconsistent start mark—then the change—use one labelled origin—then the expected benefit—comparable distances.

A next-step limit

Testing a second car adds evidence about that car; it still does not establish every car or surface.

Your written practice

Show your working on paper and enter your answer here. If it does not match, compare the model and try again.