Step-by-step graph drawing

  1. Choose the correct axes: independent variable on the x-axis, dependent variable on the y-axis
  2. Label both axes with the variable name AND unit (e.g. "Temperature / °C")
  3. Choose an appropriate scale that uses at least 50% of the grid. Each small square should represent a sensible value (1, 2, 5, 10, 20, 50: not 3 or 7)
  4. Plot points accurately using small crosses (×) or dots with circles
  5. Draw a line of best fit: either a smooth curve or a straight line, depending on the trend. Do NOT join dot-to-dot unless specifically instructed
  6. Give the graph a title

Line of best fit vs joining points

A line of best fit is a smooth curve or straight line that follows the general trend of the data. It does not need to pass through every point: some points may fall above or below the line. This is appropriate when you expect a continuous relationship (e.g. Enzyme rate vs temperature).

Joining points (dot-to-dot) is only used when each value is a distinct category (e.g. Bar chart with discrete groups) or when the question specifically asks for it.

Common errors that lose marks

  • Axis labels missing units: "Temperature" loses a mark; "Temperature / °C" earns it
  • Scale that does not use the grid: if your data goes up to 45 and your y-axis goes to 200, the graph will be cramped and hard to read
  • Inconsistent scale: each interval must represent the same value (not 10, 20, 50, 100)
  • Jagged line of best fit: use smooth curves, not shaky hand-drawn lines