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## Monday, February 15, 2010

### Exemplary 7th Grade POW Essay

This week’s POW was called “Join The Bacteria Team.” In the problem, Justin was in Mr. Bott’s math class, on Friday afternoon right before spring break, and he notices that the tables are dirty (there were 2 bacteria on the table originally). To solve this problem, I had to figure out how many bacteria would be on the table after spring break was over, if the number of bacteria doubled every hour. I had to make a table to show the growth of the number of bacteria as well as a graph. This problem was about using scientific notation and finding patterns.

My first step in this problem was to make the table. To do this, I selected a time in the afternoon for the growth to start (2 pm on Friday), and end (9 am on Monday). Then, I carefully filled the table out, starting at 2 and doubling each number, (for example 2+2=4, 4+4=8) making sure to use scientific notation when the numbers got larger than a couple thousand. After filling out all of the table, and rechecking my work multiple times, I started making the graph. To make the graph, I split up the data into sections, meaning that I graphed for everyday separately. This allowed me to see a pattern that the data goes up at an even pace very quickly (see sample of graph and table below). I used a calculator to ensure that all my calculations were correct.

The total number of bacteria after spring break was about 1.13 times 1071. I know my solution is correct because all the calculations were check and I compared my results with other students after I had solved the problem. There are other solutions to this problem because some people might have chosen to start at 1 pm or later and chosen to end at 8 pm or earlier. Plus, since this problem will never have an exact answer, there will be many variations.

This problem was very interesting to me because I had never really thought that bacteria grew that quickly till I solved the problem. This problem challenged me because at first I did not realize that the graph would be so difficult to make, especially when there are so many huge numbers. This POW reminded me of counting beans in 1st grade, because there were so many beans and the number just kept getting larger and larger. I managed my time fairly well, however I could have done more work over the week rather than the weekend. Next time, I would like to try and find a rule for the POW which will make it easier to complete the table.