replacement for ht emetric sustem; based on decimal system sinf the number 10 as the base unit; includes the meter: (m), second (s), and kilogram (kg)
dependent variable
factor in an experiment that can change if the independent variable is changed
atmosphere
blanket of gases surrounding Earth that contains about 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases such as argon, carbon dioxide, and water vapor
environmental science
study of the interactions of humans with environment
hydrosphere
all the water in Earth's oceans, lakes, seas, rivers, and glaciers plus all the water in the atmosphere
scientific model
an idea, a system, or a mathematical expression that represents the idea being explained
hypothesis
a testable explanation of a situation
control
standard for comparison in an experiment
scientific methods
a series of problem-solving procedures that help scientists conduct experiments
biosphere
all of Earth's organisms and the environment in which they live
