Capture-Recapture Population Estimates - AQA GCSE Biology Calculation Practice Book

The Lincoln index formula looks straightforward but students lose marks by substituting values into the wrong positions. This AQA GCSE Triple Biology workbook builds fluency with 12 scaffolded questions using the EVERY method framework.

The EVERY method breaks each calculation into clear steps: Equation, Values, Enter values into the equation, Rearrange if needed, Your units. Every question has a structured EVERY table for students to complete, building a consistent problem-solving habit. Questions get progressively harder: Q1-3 are straightforward, Q4-6 introduce unit conversions, and Q7-12 require rearranging the formula.

What's inside:

- 12 progressive questions on Capture-Recapture (population = first catch x second catch / number recaptured)

- Structured EVERY method table on every question page

- Progressive difficulty: simple substitution, then unit conversions, then rearranging

- Self-assessment tracker with "What made me stuck?" reflection checklist

- Full worked answers for all 12 questions using the EVERY method steps

AQA specification reference: 4.7 Ecology (Triple Biology only)

Capture-recapture questions ask students to estimate population size from fieldwork sampling data. They use the Lincoln index: total population = (number in first sample x number in second sample) / number recaptured in second sample.

Common student mistakes this workbook addresses: dividing by the wrong value (using total second catch instead of recaptured), not recognising when the assumptions of the method are violated (e.g. migration, births, deaths), rounding population estimates to whole numbers, and confusing this formula with other ecology calculations.

Suitable for AQA GCSE Biology (Triple only, not Combined Science). Works for both foundation and higher tier students.

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