Maggie Amsler studies the chemical ecology of the Antarctic Peninsula. She measures the growth rate of aquatic plants. One thing she studies is how underwater plants grow in response to light or to a lack of light.
She is doing one experiment on the kinds of algae that grow here. (If you are wondering why algae are important, take a look at the food and other items in your home. Algae are everywhere!! And, they are very important in the marine environment.)
Maggie and her team call this experiment the "substrate experiment". A substrate is an artificial surface placed into the ocean, so that plants or animals can be attached to it. She and her team have placed 12 concrete platforms, or substrates, 20 feet deep underwater near an offshore island. Each of these platforms is a square 40 cm on a side and about 5 cm thick. It has plastic rods at each of the corners, sticking up about 25 cm from the substrate. (Here's the math: what is the volume of concrete contained in each substrate?)