Washington Comprehensive Assessment of Science (WCAS) Grade 8 cheat sheet

Speed = distance ÷ time; velocity adds direction, and acceleration is any change in speed or direction.

Newton's first law: an object at rest or in uniform motion stays that way unless a net force acts on it.

Newton's second law: net force = mass × acceleration (F = ma); doubling mass halves acceleration for the same force.

Newton's third law: forces come in equal and opposite pairs acting on two different objects.

Kinetic energy = ½mv²; potential energy from gravity = mgh (mass × gravity × height).

In a closed system, energy is conserved but transforms among kinetic, potential, thermal, sound, and light forms.

Waves carry energy, not matter; amplitude relates to energy, frequency × wavelength = wave speed.

In a series circuit, current is the same everywhere and resistances add; in parallel, voltage is equal across branches.

Substances have characteristic density (mass ÷ volume) and melting/boiling points that help identify them.

Cells are the basic unit of life; cell theory states all organisms are made of cells and cells come from existing cells.

Photosynthesis (in chloroplasts) converts light, water, and CO2 into glucose and oxygen; respiration releases that energy.

Organelles have specific jobs: nucleus stores DNA, mitochondria release energy, ribosomes build proteins, membrane controls entry.

DNA carries genetic instructions in genes; chromosomes are passed to offspring during reproduction.

Punnett squares predict offspring genotype and phenotype ratios from parental alleles.

Natural selection requires variation, heritable traits, competition for resources, and differential survival and reproduction.

Food webs model energy flow; producers capture energy, consumers transfer it, and decomposers recycle nutrients.

Ecosystems depend on both living (biotic) and nonliving (abiotic) factors such as water, temperature, and soil.

Body systems interact: the circulatory, respiratory, and digestive systems cooperate to deliver nutrients and oxygen to cells.

Earth's layers: crust (thin, rocky), mantle (hot, slow-flowing rock), outer core (liquid metal), inner core (solid metal).

Plate tectonics: lithospheric plates move over the mantle; convergent, divergent, and transform boundaries produce different landforms and hazards.

Earthquakes occur where stress releases along faults; P waves arrive first, S waves second, and surface waves cause the most damage.

The rock cycle links igneous, sedimentary, and metamorphic rocks through melting, cooling, weathering, erosion, and heat/pressure.

The water cycle moves water by evaporation, condensation, precipitation, and runoff, driven mainly by the Sun's energy.

Earth's rotation (daily) causes day and night; its tilted axis and revolution (yearly) cause seasons.

Moon phases result from the Moon's orbital position relative to Earth and the Sun; eclipses require aligned orbits.

The solar system has eight planets orbiting the Sun; gravity governs orbital motion and decreases with distance.

Weathering breaks rock in place; erosion transports the pieces; deposition lays them down, building soil and landforms.