Year 7 Science · AC9S7I03

Equipment, precision and data recording

Accessible → standard → challenge. Justify choices using range, capacity, resolution, accuracy, precision and recording conventions.

  1. You expect 20–70 °C. Choose between thermometers 0–50 °C, −10–110 °C and 80–150 °C. Justify.
  2. Why is a 25 mL measuring cylinder generally preferable to a 1 L beaker for measuring 15 mL?
  3. Distinguish resolution, precision and accuracy.
  4. A balance reads 5.42 g repeatedly for a 5.00 g reference mass. Describe its precision and accuracy.
  5. Explain how parallax can affect an analogue scale and how to reduce it.
  6. A stopwatch displays 4.83 s. Why does this not prove the timing is accurate to 0.01 s?
  7. Design headings for a table recording temperature every 30 s for 5 min.
  8. Why should units usually appear in the column heading rather than after every value?
  9. A temperature logger samples once every 10 min during a 2-min reaction. Identify the problem and improve it.
  10. A plant-identification app gives 62% confidence from one photo. What should the student do before recording the species as confirmed?
  11. Raw readings are 12.1, 12.2, 18.9, 12.0 °C. Should 18.9 be silently deleted? Explain the correct process.
  12. Plan equipment for measuring how light intensity changes with distance from a lamp. Name the equipment, units, useful range/resolution considerations and one digital-tool check.

Answers / marking guidance

1–4

1 −10–110 °C covers the whole expected range. 2 Its capacity is close to the required volume and its graduations are designed for volume measurement. 3 Resolution = smallest readable increment; precision = fineness/repeatability; accuracy = closeness to reference. 4 Precise but inaccurate: repeated values agree, but are systematically 0.42 g high.

5–8

5 Viewing from an angle shifts the apparent scale position; read at eye level. 6 Display resolution is not the same as total measurement accuracy; reaction time/calibration can dominate. 7 Time (s) and Temperature (°C), with rows every 30 s. 8 It keeps data cells numeric and makes the unit unambiguous for the whole column.

9–12

9 Sampling interval is longer than the event; sample much more frequently, for example every second if the sensor supports it. 10 Cross-check another image/feature with a reliable identification source or expert. 11 Check transcription, instrument/method and repeats; retain/flag or justify exclusion. 12 Light sensor/lux meter, ruler/tape measure, fixed lamp; record distance (cm or m) and light intensity (lux); ensure sensor range/resolution suits expected values and verify calibration/setup/sampling.