3: Draw exponential growth

Hopefully at this point in your career as a biology student, you have seen a graph of exponential growth. Rather than show you a picture right away, use your mouse to draw an exponential curve (specifically, starting at 1 and doubling at each timestep) on the graph below.

Then click on the “graph” button to see how close you got.

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way ahead of youSo, on regular graph paper, exponential growth looks like a curve heading up (or accelerating). When a few bacteria double, that only gives us a few more. But when thousands of bacteria double, we get thousands more. When a million bacteria double, we get a million more.

Pretty soon we’ve got a real problem.

(Note for people who are way ahead: in a few screens we’ll find out that the graph-on-regular-paper doesn’t work very well when talking about bacteria, and we’ll fix that problem. But we’re not there yet.)