science

• Oxygen makes up about 21% of the air we breathe.
• The Earth's atmosphere is made up of nitrogen, oxygen, carbon dioxide, water vapor, and trace amounts of other gases.
• An independent variable is the one being changed by the experimenter
• Experimentation is a crucial step in the scientific method where researchers test the hypothesis through controlled tests and data collection.
• The human body is made up of different systems, including the nervous system.
• Nitrogen makes up about 78% of the air we breathe.