Processing and evaluating
🎯The five strands
At Year 5 the strands ask you to:
- i. Present collected and transformed data. Tables and graphs, correctly, with units.
- ii. Interpret data and explain results using scientific reasoning.
- iii. Evaluate the validity of the hypothesis against what the data actually showed.
- iv. Evaluate the validity of the method.
- v. Explain improvements or extensions to the method.
📊Presenting and transforming data
Transformed is the key word in strand i. Raw readings are not enough; you are expected to process them — average the repeats, calculate the quantity you actually want, and then graph it. A results table should show the independent variable, every repeat, the mean, and the processed quantity, each column headed with its unit. The graph should have the independent variable on the horizontal axis, sensible scales, plotted points and a line or curve of best fit — not a dot-to-dot.
📈What moves you up the bands
A 1–2 response presents the numbers and states an obvious trend. A 7–8 response presents processed data correctly, interprets the pattern with physics, tests the hypothesis against the evidence, and then turns a critical eye on its own method — naming specific limitations, spotting anomalies, and proposing improvements that would actually address them. The move that earns the top band is self-criticism: a good evaluation reads as if written by someone trying to catch their own mistakes.
✏️A worked evaluation
Interpretation (strand ii): The straight line through the origin shows the period is proportional to the square root of the length, not to the length itself. This matches the physics of simple harmonic motion, where the period depends on \( \sqrt{L} \); doubling the length multiplies the period by about 1.4, not 2, which is exactly what the data show.
Evaluating the hypothesis (strand iii): The hypothesis — that period increases with length, as a square-root relationship — is supported. It is important to say which part is supported: the direction and the shape both hold, so the hypothesis stands as a whole rather than merely “being right”.
Evaluating the method (strand iv): One point at 0.60 m sits noticeably above the line — a likely anomaly, probably because the bob was released at too large an angle on that run, breaking the small-angle condition. Reaction time in starting and stopping the watch is the largest source of random error even after timing ten swings; and the length was measured to the centre of the bob by eye, which adds a small systematic uncertainty. These are specific weaknesses, tied to this experiment, not a generic “human error”.
Improvements (strand v): Use a photogate and electronic timer to remove reaction time entirely; fix the release angle with a marked card so it is identical every time; and measure to the centre of mass of the bob with a set square. An extension: repeat with bobs of different mass to confirm, as the theory predicts, that mass makes no difference to the period.