Everything grade 3 science expects you to be able to say, in 65 short statements. Read it the night before a test, or use it to decide which skill quiz to take next.
Science and Engineering Practices
- A fair test changes one variable and keeps everything else the same.
- Repeat a test several times so one strange result does not fool you.
- An observation is what you notice. An inference is what you conclude from it.
- Data is what you collected. Evidence is data used to back up a claim.
- A model is a stand-in for something real: a drawing, a diagram, or a physical build.
- Engineers define the problem and its limits before designing anything.
- A failed prototype is information. Change one thing and test again.
Words to know: Observation, Inference, Hypothesis, Prediction, Variable, Independent variable, Dependent variable, Controlled variable, Fair test, Control group, Data, Evidence, Claim, Reasoning
Matter and Its PropertiesMatter and Its Properties
- Matter has mass and takes up space, even when you cannot see it, like air.
- Solids keep their shape, liquids take the shape of the container, gases fill it completely.
- Adding thermal energy melts and evaporates. Removing it condenses and freezes.
- Dissolving is a physical change. The salt is still there, spread through the water.
- Bubbles, a color change, or unexpected heat usually signal a new substance formed.
- Weigh a sealed container before and after: the total mass does not change.
- Materials are identified by their properties, not by how they look at a glance.
Words to know: Matter, Mass, Volume, Property, Solid, Liquid, Gas, Melting, Freezing, Evaporation, Condensation, Mixture, Solution, Dissolve
Forces and MotionForces and Motion
- A force is a push or a pull. It takes a force to start, stop, or turn something.
- Balanced forces leave motion unchanged. Unbalanced forces change it.
- Gravity pulls everything toward Earth's center, which is why things fall down.
- Friction acts against sliding. Smoother surfaces mean less friction.
- Magnets attract iron, and like poles push each other apart.
- Gravity and magnetism work at a distance, without touching.
- Patterns in motion let you predict where an object will be next.
Words to know: Force, Motion, Speed, Balanced forces, Unbalanced forces, Gravity, Weight, Friction, Magnet, Magnetic pole, Contact force, Non-contact force, Simple machine
EnergyEnergy
- Moving objects have kinetic energy. Faster and heavier means more of it.
- Position and stretch store potential energy, ready to be released.
- Thermal energy always moves from the warmer object to the cooler one.
- Temperature measures how fast particles move on average, not how much energy is present.
- Metals conduct energy well. Plastic, wood, and air are insulators.
- A circuit must be a complete loop for current to flow.
- Energy changes form constantly: electrical to light, chemical to motion.
Words to know: Energy, Kinetic energy, Potential energy, Thermal energy, Temperature, Heat transfer, Conductor, Insulator, Electric circuit, Current, Energy transfer, Energy transformation, Renewable resource, Nonrenewable resource
Waves and InformationWaves and Information
- Waves carry energy from place to place without carrying the material along.
- Bigger amplitude means a louder sound or a brighter light.
- Sound comes from vibration and needs a material to travel through.
- Faster vibrations make a higher pitch.
- Light travels in straight lines until it reflects, refracts, or is absorbed.
- Opaque objects block light and cast sharp shadows. Transparent ones let it through.
- Patterns in light and sound can be used to send information over a distance.
Words to know: Wave, Amplitude, Wavelength, Vibration, Pitch, Volume (loudness), Reflection, Refraction, Absorption, Transparent, Translucent, Opaque, Shadow
Cells, Structures and Life ProcessesCells, Structures and Life Processes
- Every organism has structures, and each structure does a job that helps it survive.
- Plants make their own food using air, water, and light energy.
- Life cycles differ between organisms but always include birth, growth, and reproduction.
- Offspring resemble their parents but are not identical to them.
- Some traits are inherited and some are gained during life.
- The environment can affect how a trait turns out, such as a plant's height.
- Animals sense a stimulus, process it, and respond.
Words to know: Organism, Trait, Inherited trait, Acquired trait, Life cycle, Metamorphosis, Structure, Function, Adaptation, Photosynthesis, Stimulus, Response, Heredity, Variation
Ecosystems and HeredityEcosystems and Heredity
- Producers make food, consumers eat it, decomposers recycle what is left.
- Energy in a food web starts with the Sun and moves one direction through the chain.
- Populations grow when resources are plentiful and shrink when they are scarce.
- Organisms compete for food, water, space, and shelter.
- A change to one part of an ecosystem ripples out to the others.
- Some animals survive better in groups than alone.
Words to know: Ecosystem, Habitat, Population, Community, Producer, Consumer, Decomposer, Food chain, Food web, Predator, Prey, Competition, Resource
Evolution, Fossils and AdaptationEvolution, Fossils and Adaptation
- Fossils are evidence of organisms and environments from long ago.
- Rock layers hold older fossils deeper down.
- Traits that help an organism survive become more common over many generations.
- When the environment changes, some organisms move, some adapt, and some die out.
- Camouflage, sharp claws, and thick fur are all survival advantages in the right place.
Words to know: Fossil, Extinct, Ancestor, Survival advantage, Camouflage, Environmental change
Earth and Space SystemsEarth and Space Systems
- Weather is right now. Climate is the long-run pattern for a region.
- Water cycles endlessly through evaporation, condensation, precipitation, and collection.
- Weathering breaks rock apart, erosion carries it away, deposition drops it somewhere new.
- Earth's rotation causes day and night. Its revolution takes one year.
- The Moon's phases repeat in a predictable cycle of about a month.
- The Sun looks brighter than other stars only because it is far closer.
- Which constellations you can see changes with the season.
Words to know: Weather, Climate, Precipitation, Water cycle, Groundwater, Weathering, Erosion, Deposition, Landform, Rotation, Revolution, Orbit, Axis, Star
Earth, Human Activity and EngineeringEarth, Human Activity and Engineering
- Natural resources are not spread evenly across Earth.
- People can reduce their impact by conserving, reusing, and recycling.
- Design solutions can lessen the damage from floods, wind, and erosion.
- You cannot stop an earthquake, but you can design for one.
- Every solution has trade-offs. Compare them against the criteria and constraints.
Words to know: Natural resource, Natural hazard, Conservation, Pollution, Recycling, Watershed, Erosion control