Demonstration for surface area to volume ratio

So, surface area to volume ratio is a common concept in Science…

In digestion, they learnt that food are broken into small pieces so that it has larger surface area to volume ratio for enzymes to work on.

But, it’s hard to student to grasp the concept. They don’t get it how food in smaller pieces have larger exposed surface area to volume ratio.

So, here’s a simple demonstration.

First, make 2 jelly using red cabbage (reason being it’s a natural pH indicator) with identical moulds. Cut only 1 of the jelly into quarters. Then, add them into container of equal volume of lye water (alkaline solution).

Due to red cabbage being natural pH indicator, the jelly will change colour in alkaline solution (yellow in strong alkaline). As seen, the jellies cut in quarter turned yellow faster than the larger jelly because it has larger surface area to volume ratio.

2 jellies using identical mould. Only 1 jelly is cut into quarters.
The results of the demonstration.

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