Bacteria reproduce by binary fission. They break in half and one becomes two. I use this topic to link math and science when we study bacteria and viruses. I start off with the question: If you start with a penny and double it every day, how many dollars will one have in one month? Let the month have 31 days. At first, they think it might be a hundred dollars or a thousand. But I have them do the math by doubling the number 31 times and see what they come up with.

After a while, someone in class usually gets the correct answer. The students are amazed to find that a person would have over 21 million dollars. This example shows the power of exponential growth.

The other day, I saw a good video about how bacteria communicate with one another given that they are so small and only one cell. Seems that they put out certain molecules to help them communicate. Check out the video from TED, it’s very interesting.