Scientific Method Vocabulary Practice This activity will help you review science method vocabulary. Tools A B constants all variables that remain the same for both control and experimental groups control group the comparison group that is identical to the experimental group except it doesn't get treated with the independent variable experimental group receives the treatment with the independent variable controlled experiment have both a control group and experimental group data what science bases truth on dependent variable what the experimenter measures in response to the change independent variable what the experimenter changes experiment designed to carefully test the hypothesis extraneous variables extra conditions that are not the same for both groups hypothesis educated guess null hypothesis stated in terms of "will not affect" or "will be no difference" qualitative data observational judgments that are not standard quantitative data standardized measurements science truth-finding system basing truth on data scientific theory a hypothesis that has withstood the test of time and many experiments atom smallest particle of an element molecule 2 or more atoms organelle tiny units of cells that perform a particular function cell basic unit of structure and function of living things tissue groups of like cells working together organ a group of tissues working together organ system groups of organs working together to perform a function organism an individual living thing population group of the same species in which all members have mating access to each other community a group of populations interacting with each other ecosystem communities interacting with the physical environment biome a large ecosystem with similar plant types (grassland) biosphere all biomes on earth