the factor that is manipulated in an experiment which causes another factor to respond
the variable that is directly changed by a scientist in an experiment which results in the change of other variables
the variable that results in the change of other variables; time (seconds, days, years, etc.) is an independent variable
a scientist conducting an experiment will only change one independent variable while holding all other variables constant
Example: In an experiment scientists measure if fertilizer has an effect on plant growth. Some plants are given fertilizer and some are not. The height of the plants are recorded. The fertilizer treatment or lack of fertilizer is the independent variable