Scientific vocabulary can feel intimidating. But most of the words that seem technical are just precise versions of ideas we already think about every day. Here are ten terms that are worth having in your vocabulary — whether you're in a classroom, reading the news, or just trying to make sense of the world.
A testable prediction about what you expect to happen in an experiment. A hypothesis isn't a guess — it's an educated, specific claim that can be proven wrong. "Plants grow taller with more sunlight" is a hypothesis. "Plants are nice" is not.
The movement of water molecules through a semipermeable membrane from an area of lower solute concentration to higher solute concentration. This is why your fingers wrinkle in the bath, why plants absorb water from soil, and why salting a slug is unfortunately effective.
The tendency of an object to resist changes to its state of motion. A still object wants to stay still. A moving object wants to keep moving. Newton's first law describes inertia — and it's why you lurch forward when a car stops suddenly.
A measure of disorder or randomness in a system. The second law of thermodynamics says entropy always increases over time in a closed system. In plain terms: things fall apart. A clean room gets messy on its own. It never gets clean on its own.
The process by which a cell divides to produce two identical daughter cells, each with a complete copy of the original DNA. Mitosis is how you grow, heal wounds, and replace old cells. Your body performs it trillions of times over your lifetime.
The fourth state of matter (alongside solid, liquid, and gas), consisting of ionized gas with freely moving electrons. Plasma makes up more than 99% of the visible universe — stars are made of it. On Earth, you've seen it in lightning bolts, neon signs, and the northern lights.
A substance that speeds up a chemical reaction without being consumed in the process. Enzymes are biological catalysts — they make reactions happen in your body that would otherwise take millions of years. Catalytic converters in cars use platinum and palladium to break down exhaust pollutants.
The fundamental particle of light and all electromagnetic radiation. Photons have no mass and always travel at the speed of light in a vacuum. Every time you see anything, it's because photons have bounced off it and entered your eye. The light from the sun is photons that traveled 93 million miles in about 8 minutes.
The complete set of genetic instructions for an organism, encoded in DNA. Your genome contains about 3 billion base pairs and is packed into nearly every cell in your body. If you unraveled all the DNA in a single human cell and stretched it out, it would be about 2 meters long.
A variant of an element that has the same number of protons but a different number of neutrons. Carbon-12 and Carbon-14 are both carbon — they have 6 protons — but carbon-14 has 2 extra neutrons. This makes it radioactive and useful for dating ancient organic materials in a technique called radiocarbon dating.