Surface area to volume ratio (Edexcel GCSE Biology & Combined Science)

This lesson uses step by step guides to describe how to calculate the surface area to volume ratio. The PowerPoint and accompanying resources are part of the first lesson in a series of 2 lessons which have been designed to cover the detail of points 8.2 and 8.3 of the Edexcel GCSE Biology & Combined Science specifications.

The calculation of the SA/V ratio can be an area of the course that students find difficult so this lesson breaks the calculation into parts to guide them through each step. The students are shown how to calculate the surface area, then the volume and then how to express the answer of the division calculation as a ratio against 1. After each step, the students are given the opportunity to apply their understanding and all questions have mark schemes with full workings embedded into the PowerPoint to allow the students to self-assess. Students also tend to struggle to see the relevance to Biology so the remainder of the lesson involves the calculation of the ratio for the alveoli in the human body. Students will discover that the surface area to volume ratio is significantly increased in these gas exchange surfaces which leads into the upcoming lesson on the adaptations of the alveoli to overcome the overall low ratio in larger organisms.