iVisit workshop - Surface area and volume
Here are materials from an online iVisit professional development workshop.
We started with a simple activity -- take two ice cubes, and crush one. Which one melts faster? The crushed one, because the exchange of heat between the ice cube and the environment occurs at the surface, and crushing increases the surface area.
A hunk of iron won't burn, but steel wool will, due to the increased surface area.
Again, a hunk of cornstarch won't burn, but when sifted it will. Farmers are well aware of this, and have to be careful of combustion in their corn silos.
Yes, like mentos and diet coke, it has to do with surface area. But in this case, the surface area allows faster solubility, which enables a faster chemical reaction.
Video 4 - Gelatin with acid/base indicator
The surface area to volume ratio affects how quickly substances can diffuse into a shape, which is important in cell biology. This elegant activity uses gelatin and cabbage juice indicator. Recipe for cabbage juice indicator.
For more connections to biology, see below.
Here's the math behind these activities... construct different sized cubes and measure their surface area to volume ratio.
