Selma's Experiment on Streptococcus Bacteria Reproduction

The Experiment

Selma wants to find out at which temperature Streptococcus bacteria reproduce the fastest. She places the same size sample of the bacteria on 10 different Petri dishes filled with nutrient agar. Each dish is then placed in different incubators set at varying temperatures. After three hours, Selma removes the dishes from the incubators and observes the size of the bacterial colonies.

The Variable in the Experiment

The variable in Selma's experiment is the temperature. The different temperatures set in each incubator are the independent variables that Selma is testing to determine their effect on the reproduction rate of Streptococcus bacteria. By changing the temperature, Selma is able to measure how this factor influences the growth of the bacterial colonies.

What is the variable in Selma's experiment?

A variable is what changes in the experiment. In Selma's case, the variable is the temperature at which the Petri dishes are placed in the incubators.