The Growth Curve Of Bacteria

Collaboration Between Biology and Algebra 1 Classes

Germs are everywhere! Right? Yes! Even if you clean everyday they are still there.

In Biology we have been investigating the growth of bacteria on surfaces we touch every day. We each had an assignment and took off to swab the school. We checked the growth 5 different days over 2 weeks. Surfaces we swabbed were door knobs, bathroom doors and stall door handles. Also the microwave handle and the printer.

Data was collected each time, recorded in a spreadsheet, and analyzed for 2 weeks. It took awhile but once the specimens start growing, they showed exponential growth the first few weeks and then leveled out. That’s because the rate of cell growth and cell death is about equal and so the graph levels out. As cell death takes over, the growth curve drops exponentially.

Oh yeah, the printer has more bacteria than any of the other places.

We sketched a graph showing the growth of our bacteria (y-axis) over time (x-axis).

Bottom line: Wash your hands and use soap!