Skin Area

Students work in groups to estimate length, weight, area and volume of objects in the classroom, before measuring and calculating the same values. They then move on to estimating the total surface area (i.e. skin area) of a volunteer from their group. This can be done by modelling the body as a series of regular 3D shapes. Finally, they compare their estimates to values obtained from a series of suggested formulae for estimating skin area from height and weight.

Prior knowledge

This is a readily accessible task, with students only needing basic measurement and estimation skills to get started; they will then need to calculate percentage errors to compare results. The modelling aspects of the main task are more demanding, and a suggested approach can be offered, if needed, using the materials provided in the accompanying presentation. Students will need to use a scientific calculator to enter the relatively complicated formulae provided in the presentation.

Relevance to Core Maths qualifications

  • AQA
  • C&G
  • Eduqas
  • Pearson/ Edexcel
  • OCR

Suggested approaches

This task is designed for group work, and should take up to three hours. The accompanying presentation suggests ways in which each stage of the activity can be organised.


The PowerPoint presentation provided includes full guidance notes for each stage of the activity. Measuring equipment (rulers, scales, tape measures) will be needed, and students will need to use a scientific calculator or spreadsheet. For the starter activity, you will need to identify a number of objects to be measured (and adjust the relevant slide accordingly).

Possible extensions

Students could explore the behaviour of the four suggested formulae over a range of values of height and weight, exploring whether they generate similar values.


This activity was developed by Penri Thomas of St Brendan’s Sixth Form College.