Estimating and measuring

Strand: Ratio, Proportion and Rates of Change Substrand: Measures Sparx code: U102 Sparx levels: 1, 2

Key steps (method)

• Write down the given information and what you are asked to find for Estimating and measuring.
• Choose a representation that fits the topic (diagram / table / algebra / graph) and set it up neatly.
• Write the units you’re measuring in and convert first if needed (mm↔cm↔m, g↔kg, etc.).
• If using a diagram/scale, measure carefully and apply the scale factor before answering.
• Apply the topic rule(s) step-by-step, showing enough working to keep method marks.
• Substitute values carefully (watch brackets, negatives, and order).
• Write the final answer clearly with correct units/rounding.
• Do a quick check that the answer is sensible for the context.

Common mistakes

• Unit conversion slips (cm vs m; minutes vs hours).
• Reading the wrong mark on a scale or not applying the given scale factor.
• Using the right idea but the wrong rule/interpretation for the topic.
• Skipping key working so method marks can’t be awarded.
• Sign/bracket errors when substituting or rearranging.
• Rounding too early or to the wrong accuracy.
• Not checking whether the answer is reasonable.

Notes