act science

Atoms. Atoms are the basic units of matter.
Molecules. Two or more atoms chemically bonded together.
Elements. Pure substances made of one type of atom.
Compounds. Substances made of multiple elements chemically bonded together.
Chemical Formulas. Subscripts indicate the number of atoms.
Chemical Equation Arrows. → means “produces” or “yields,” while ⇌ indicates that a reaction occurs in both directions (equilibrium).
Concentration. The amount of substance present in a certain volume.
Dissolving. When one substance becomes evenly distributed in another.
Gas vs Liquid vs Solid. Solids have a fixed shape and volume, liquids have a fixed volume and change shape, and gasses have no fixed shape or volume.
- Condensation: Gas → liquid
- Evaporation/Vaporization: Liquid → gas
- Melting: Solid → liquid
- Freezing: Liquid → solid

Density. Objects with high density have more mass packed into a given volume. Objects float if they are less dense than the fluid around them.
Conservation of Mass. Matter is not created or destroyed during chemical reactions.

Cell. Basic unit of life.

Tissue. Group of similar cells working together.

Organ. Group of tissues working together for a specific function.

Organism. An individual living thing.

Species. A group of organisms capable of reproducing together.

Ecosystem. Living organisms interacting with their environment.

Photosynthesis. Plants use sunlight to produce glucose. Plants need sunlight, water, and carbon dioxide.

Cellular Respiration. Cells break down glucose to release energy.

Hormones. Chemical messengers in organisms.

DNA. Genetic material carrying instructions for life.

Endotherm vs Ectotherm.
- Endotherm. Animals that generate body heat internally, like mammals and birds.
- Ectotherm. Animals that rely mostly on environmental heat, like reptiles and amphibians.

Reptiles. Cold-blooded vertebrates with scales.

Amphibians. Cold-blooded vertebrates that usually live partly in water.

Mammals. Warm-blooded vertebrates with hair/fur that produce milk.

Fish. Aquatic vertebrates that use gills.

Osmosis. Movement of water across a membrane from high water concentration to low water concentration.

Speed. Distance traveled per unit time.
Velocity. Speed with direction.
Acceleration. Rate of change in velocity.
Force. A push or pull.
Gravity. Force pulling objects toward Earth.
Friction. Force resisting motion between surfaces.
Energy. Ability to do work.
Kinetic Energy. Energy of motion.
Potential Energy. Stored energy.
Temperature vs Heat.
- Temperature. Measure of average particle motion.
- Heat. Transfer of thermal energy.
Frequency. How often something occurs. A common example is sound waves per second.
Waves. Transfer energy through matter or space.
Sound Waves. Mechanical waves that travel through matter.
Light. Electromagnetic radiation.
Electrons. Negatively charged particles.
Protons. Positively charged particles.
Neutrons. Neutral particles.
Electrical Charges. Opposite charges attract while like charges repel.
Magnetic Fields. Regions where magnetic forces act.
Mass. Amount of matter in an object.

Weather. Short-term atmospheric conditions.

Climate. Long-term weather patterns.

Erosion. Movement of sediment by wind, water, or ice.

Sediment. Small particles of rock or soil.

Albedo. Reflectiveness of a surface.

Solar Radiation. Energy coming from the Sun.

Atmosphere. Layer of gases surrounding Earth.

Tectonic Plates. Large moving sections of Earth’s crust.

Fault Line. Boundary where tectonic plates meet.

Fossils.Preserved remains or traces of ancient organisms.