Ocean Math...and how 'bout those whipped cream waves???

We just began a little study using the amazing book, Awesome Ocean Science! On p. 7-8 it describes how to make a pie that compares the ratio of the earth's water to land. We modified it for a gluten-free edible ocean math lesson.

The book says that 70% of the earth is covered with water, 30% land. We decided to use blue jello in a 9x13 baking dish to show the water. So the first question...how could we divide the pan into sections to accurately model 70%?

We problem solved by drawing diagrams on the whiteboard. My student knew he wanted to begin by dividing the area of the pan in half, lengthwise. He also knew that he wanted 10 sections, each representing 10% of the earth. At first he thought he could make 5 horizontal cuts to make 5 horizontal sections. Quickly realizing that 5 cuts made 6 sections, he modified, making 4 horizontal cuts. We measured the pan to determine that each cut would need to be somewhere between 2 and 3 inches in length. This wasn't exact measuring...a simple estimate made cuts that gave us 10 more-or-less equal sections.

The boys then covered 30% of the surface with blueberries to indicate land, leaving the other 70% to show water. Finally, a few "white waves" (whipped topping) finished off the ocean surface.

Yummy math!