Praxis Middle School Science flashcards
Praxis Middle School Science · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Density formula
- Density equals mass divided by volume (D = m/V). It determines whether an object floats or sinks in a fluid and is expressed in units such as g/cm³.
- Newton's second law
- The net force on an object equals its mass times its acceleration (F = ma). Greater force or smaller mass produces greater acceleration.
- Kinetic energy formula
- Kinetic energy equals one-half the mass times the square of velocity (KE = ½mv²). Doubling speed quadruples kinetic energy because velocity is squared.
- Atomic number
- The number of protons in an atom's nucleus, which identifies the element. In a neutral atom it also equals the number of electrons.
- Isotope definition
- Atoms of the same element with equal protons but different numbers of neutrons. They share chemical properties but differ in mass number.
- pH scale meaning
- A measure of hydrogen ion concentration from 0 to 14. Values below 7 are acidic, 7 is neutral, and above 7 is basic.
- Photosynthesis equation
- Six carbon dioxide molecules plus six water molecules, using light energy, produce one glucose molecule and six oxygen molecules.
- Plate boundary types
- Divergent boundaries spread apart creating new crust, convergent boundaries collide causing subduction or mountains, and transform boundaries slide past each other.
- Igneous rock formation
- Rock formed when molten magma or lava cools and solidifies. Slow cooling underground produces large crystals; rapid cooling at the surface produces fine crystals.
- Sedimentary rock formation
- Rock formed from sediments compacted and cemented over time, often layered, and the only rock type that can preserve fossils.
- Metamorphic rock formation
- Rock altered by intense heat and pressure without melting. Examples include marble from limestone and slate from shale.
- Speed versus velocity
- Speed is a scalar quantity describing distance per unit time. Velocity is a vector that also specifies direction of motion.
- Conservation of energy
- Energy cannot be created or destroyed, only converted between forms. Total energy in a closed system remains constant.
- Weight versus mass
- Mass is the amount of matter in an object, measured in kilograms. Weight is the gravitational force on that mass (W = mg), measured in newtons.
- Cellular respiration purpose
- The process by which cells break down glucose with oxygen to release usable energy as ATP, producing carbon dioxide and water as byproducts.
- Independent variable
- The variable deliberately changed or manipulated by the researcher in an experiment. It is the presumed cause being tested.
- Dependent variable
- The variable that is measured or observed in response to the independent variable. It is the presumed effect or outcome.
- Control group purpose
- A comparison group that does not receive the experimental treatment. It isolates the effect of the independent variable from other factors.
- Controlled variables
- Factors held constant across all experimental groups so they cannot influence the outcome. Also called constants.
- Testable hypothesis
- A proposed explanation stated so it can be supported or refuted by observation or experiment. It must be falsifiable, not merely descriptive.
- Accuracy versus precision
- Accuracy is how close a measurement is to the true value. Precision is how close repeated measurements are to each other.
- Random versus systematic error
- Random error scatters measurements unpredictably, reducing precision. Systematic error shifts all measurements in one direction, reducing accuracy.
- Significant figures rules
- Nonzero digits and captive zeros count. Leading zeros never count. Trailing zeros count only when a decimal point is present.
- Scientific notation form
- A number written as a coefficient between 1 and 10 multiplied by a power of ten. Positive exponents indicate large numbers, negative exponents small ones.
- Correlation versus causation
- Two variables changing together does not prove one causes the other. A confounding variable may explain the observed relationship.
- Mean median mode
- The mean is the arithmetic average, the median is the middle value, and the mode is the most frequent value in a data set.
- Standard deviation meaning
- A measure of how spread out data values are around the mean. A larger standard deviation indicates greater variability.
- Scientific theory versus law
- A theory is a well-supported explanation of why something happens. A law describes a consistent observed relationship, often as a formula.
- Qualitative versus quantitative data
- Qualitative data are descriptive and non-numerical, such as color or texture. Quantitative data are numerical measurements that can be analyzed statistically.
- Steps of scientific method
- A flexible sequence: observe, ask a question, form a hypothesis, design and conduct an experiment, analyze data, and draw conclusions.
- Replication in experiments
- Repeating a study or trial multiple times to confirm results are reliable. Larger sample sizes reduce the influence of chance variation.
- Metric base units
- Standard SI units include the meter for length, kilogram for mass, second for time, and kelvin for temperature.