Elijah wanted to learn more about the growth pattern of bacteria, so he performed the following experiment.

Elijah placed four bacterial colonies in a petri dish filled with nutrient broth. Then, he incubated the dish at 37°C. He planned to make systematic observations by measuring the number of colonies every twenty minutes. The diagram below shows how the dish looked at each twenty minute interval.

Total Elapsed Time

(minutes)Number of

Bacterial Colonies

04

208

4016

6032

Explanation:

close

Observations are pieces of information that are gathered using one of the five senses. Tools, such as metersticks, balances, and graduated cylinders, can be used to make observations in scientific investigations.

Systematic observations are observations that are obtained by following a preplanned method of observation. Elijah made systematic observations by counting the number of bacterial colonies every twenty minutes. The table that correctly records his observations appears below:

Total Elapsed Time

(minutes)Number of

Bacterial Colonies

04

208

4016

6032

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