A controlled experiment allows the scientist to isolate and test
a. a conclusion
b. a mass of information
c. several variables
d. a single variable

Which of the following variables present in Redi's experiment on spontaneous generation is NOT a controlled variable?
a. types of jars
b. gauze covering
c. types of meat
d. temperature at which jars were stored

Identify the INDEPENDENT VARIABLE in the following experiment.
What effect does light have on plant growth?