Study Guide

Quick meanings for every word. Pair Tier 3 words with pictures to support newcomers.

Word	Meaning
Pollution	Harmful substances introduced into air, water, or land that can damage the health of people, animals, or plants.
Precipitation	Water that falls from clouds to Earth's surface, such as rain, snow, sleet, or hail.
Temperature	A measure of how hot or cold something is.
Water	A liquid made of hydrogen and oxygen that all living things need to survive.
Acid / Acidic	Describes a substance with a pH below 7. This kind of water can be harmful in large amounts.
Alkaline	Describes a substance with a pH above 7 — another word for basic.
Aquifer	An underground layer of rock or soil that holds groundwater, often used as a source of drinking water.
Atmosphere	The layer of gases surrounding Earth, held in place by gravity.
Base / Basic	Describes a substance with a pH above 7 — the opposite of acidic.
Condensation	The process of water vapor cooling and changing into liquid droplets, forming clouds.
Evaporation	The process of liquid water warming and changing into water vapor, rising into the air.
Ground	The solid surface of land that people and animals walk on.
Hydrologic Cycle	The continuous movement of water between the atmosphere, land, and oceans, through evaporation, condensation, and precipitation.
Hydropower	Electricity generated using the force of moving or falling water.
Hydrosphere	All of Earth's water combined — oceans, rivers, lakes, ice, and groundwater.
Infiltration	The process of water soaking into the ground from the surface.
Neutral	Describes a substance with a pH of exactly 7 — neither acidic nor basic. Pure water is a common example.
Permeability	A measure of how easily water or other liquids can pass through a material.
Permeable	Describes a material that allows water to pass through it.
pH Level	A number that shows how acidic or basic a liquid is.
Porosity	A measure of how much open space exists within soil or rock — more open space allows more water to be held.
Puddling	Water collecting and standing on the surface instead of soaking into the ground.
Runoff	Water that flows across the land's surface, eventually reaching rivers, lakes, or oceans, instead of soaking in.
Salinity	A measure of how much salt is dissolved in water.
Surface	The outermost, top layer of something, such as land or water.
Sublimation	The process of a solid, like ice, changing directly into a gas without ever becoming a liquid.
Watershed	An area of land where all the water — from rain, streams, and rivers — drains to the same larger body of water.
Water Quality	A measure of how clean and safe water is for people, animals, and plants to use.