FTCE Middle Grades Science 5-9 (004) cheat sheet

Scientific method cycle: observation → question → hypothesis → controlled experiment → data analysis → conclusion → peer review and replication; a hypothesis must be testable and falsifiable.

Independent variable is manipulated by the researcher; dependent variable is measured; constants are held fixed; a control group receives no treatment or a placebo for comparison.

Validity means the experiment measures what it claims; reliability means repeated trials give consistent results. Increasing sample size and repeating trials improve reliability.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to each other. Systematic error shifts all readings the same way; random error scatters readings.

Significant figures: nonzero digits count; zeros between nonzero digits count; leading zeros do not count; trailing zeros count only with a decimal point. Addition/subtraction rounds to fewest decimal places; multiplication/division to fewest significant figures.

Scientific theory is a well-tested explanation supported by extensive evidence; a law describes a consistent relationship. Neither is a guess, and theories are not promoted into laws.

Metric prefixes: kilo (10^3), centi (10^-2), milli (10^-3), micro (10^-6), nano (10^-9). Density = mass/volume; percent error = |measured − accepted| / accepted × 100.

Bias controls include random assignment, blind and double-blind designs, placebo controls, and use of appropriate sample size; correlation does not establish causation.

Models and simulations are approximations with limits; they are revised when new evidence conflicts with predictions, which is how scientific knowledge self-corrects.

Newton's laws: an object at rest or in uniform motion stays so unless a net force acts; F = ma; every action has an equal and opposite reaction acting on a different object.

Work = force × distance (in the force direction); power = work/time; kinetic energy = ½mv²; gravitational potential energy = mgh; mechanical energy is conserved absent friction.

Speed = distance/time; acceleration = change in velocity/time; velocity is a vector (speed plus direction); on Earth free-fall acceleration g ≈ 9.8 m/s².

Density = mass/volume. Objects float when their density is less than the fluid's; buoyant force equals the weight of displaced fluid (Archimedes' principle).

Heat transfers by conduction (contact), convection (fluid currents), and radiation (electromagnetic waves, no medium needed). Heat flows spontaneously from hot to cold.

Atomic structure: protons (positive, in nucleus, define element), neutrons (neutral, in nucleus, define isotope), electrons (negative, in energy levels, define charge and bonding).

Periodic trends: groups share valence electrons and similar properties; periods show increasing atomic number. Metals lose electrons; nonmetals gain or share; noble gases are inert.

Chemical equations must balance atoms on both sides (conservation of mass). Synthesis, decomposition, single replacement, double replacement, and combustion are the main reaction types.

Acids release H⁺ (protons) and have pH below 7; bases release OH⁻ or accept H⁺ and have pH above 7; pH + pOH = 14; neutralization yields salt and water.

Cell theory: all living things are made of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells. Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

Mitosis produces two genetically identical diploid cells for growth and repair; meiosis produces four genetically varied haploid gametes and includes crossing over and independent assortment.

DNA structure is a double helix with complementary base pairs: adenine–thymine and guanine–cytosine. Transcription makes mRNA in the nucleus; translation builds protein at ribosomes.

Mendelian genetics: dominant alleles mask recessive ones; a Punnett square predicts offspring ratios. Genotype is allele combination; phenotype is the observable trait.

Photosynthesis (chloroplasts) converts CO₂ and water using light energy into glucose and oxygen; cellular respiration (mitochondria) releases energy from glucose as ATP.

Natural selection requires heritable variation, differential survival and reproduction, and environmental pressure; it acts on phenotypes and changes allele frequencies over generations.

Ecological roles: producers make food, consumers eat it, decomposers break down dead matter; energy flows one way through trophic levels while nutrients cycle.

Food chains lose roughly 90% of energy at each level (10% rule); biomass pyramids reflect this. Carrying capacity is the maximum population an environment sustains.

Homeostasis maintains stable internal conditions via feedback loops; negative feedback reverses change (body temperature, blood glucose), positive feedback amplifies it.

Earth's layers: crust, mantle, outer core (liquid), inner core (solid). Plate tectonics explains earthquakes, volcanoes, and mountain building along convergent, divergent, and transform boundaries.

Rock cycle: igneous forms from cooled magma or lava, sedimentary from compacted deposited sediment, metamorphic from heat and pressure altering existing rock.

Weathering breaks rock in place (mechanical or chemical); erosion transports sediment by water, wind, ice, or gravity; deposition lays it down.

Water cycle processes: evaporation, transpiration, condensation, precipitation, infiltration, runoff. About 97% of Earth's water is salty ocean water.

Earth's rotation on its axis causes day and night; revolution around the Sun plus a 23.5° axial tilt causes seasons and changes day length.

Moon phases result from the Moon's orbital position relative to Earth and Sun; spring tides occur at new and full moons, neap tides at quarter moons.

Solar system order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Inner planets are rocky and small; outer planets are gas or ice giants.

Weather is short-term atmospheric conditions; climate is long-term average. Air moves from high to low pressure; land heats and cools faster than water.

Relative dating uses superposition and index fossils; absolute dating uses radioactive decay half-lives (e.g., carbon-14 for recent organic material) to give numeric ages.