(d) make and record observations/measurements

The idea

This skill is about producing reliable primary data, not just looking at a specimen. Making an observation means using an instrument or your senses in a controlled, repeatable way: for example, reading a colorimeter absorbance, timing a reaction with a stopwatch, or counting stomata in a field of view. Recording means writing each value immediately, with its unit, into a pre-prepared table whose headings state the quantity and unit, so raw data are never lost or reconstructed from memory. You must choose an appropriate scale or resolution, take readings at the stated intervals, and note qualitative features such as colour or bubble production where these are the observation. Repeat readings and record them all, including anomalous ones, rather than silently discarding them.

What earns the marks

• Identifies that observations and measurements must be recorded immediately and directly, not recalled later.
• Recognises that table headings should give the quantity and its unit, with consistent decimal places or significant figures.
• Accepts that qualitative observations (for example colour change or gas bubbles) are valid recorded data alongside numerical readings.
• States that anomalous readings should be recorded and flagged rather than deleted, so they can be evaluated.
• Appreciates that the resolution and scale of the instrument chosen must suit the quantity being measured.

Common mistakes and how to put them right

• Thinking a measurement is only valid if it is numerical.

  Put it right: Qualitative observations such as colour or presence of bubbles are legitimate recorded data when they are the intended observation.

• Recording values without units or with units only in the body of the table.

  Put it right: Put the quantity and unit in the column heading and keep the cells as numbers.

• Discarding an odd reading to make results look tidy.

  Put it right: Record all readings and identify anomalies during analysis so the evaluation is honest.

Exam tips

• Read the question stem to see whether it asks about making, recording or both, and address each part explicitly.
• When judging a table, check headings for quantity plus unit and check that the number of decimal places is consistent.
• Link the choice of instrument or scale to the precision needed, rather than choosing the most elaborate equipment available.