Visionlearning Glossary

A compression wave produced by an earthquake. The “P” is from the Italian “primero,” indicating that the P-waves were the first to arrive at seismic stations.

Used in the following modules: Earth Structure

The history of reversals in polarity of the earth’s magnetic field, as recorded in magnetic minerals within igneous rocks.

Used in the following modules: Plate Tectonics I

The supercontinent which existed from about 300-200 million years ago. During this time, all of the continents were gathered into a single land mass.

Used in the following modules: Plate Tectonics I, Plate Tectonics II

the material or source from which something is derived.

Used in the following modules: Adaptation, Charles Darwin III, Chemical Bonding, DNA III, Genetics I, Genetics II, Nuclear Chemistry

The concept that the simplest explanation that fits all of the data is the most likely (and therefore the best) explanation. In different disciplines, the most parsimonious explanation may require the fewest assumptions, the fewest number of steps in a process, or the fewest interacting components in a system. Related to Ockham’s Razor.

Used in the following modules: Data: Analysis and Interpretation

A principle in science and philosophy that suggests that the simplest of two or more compatible theories is generally preferable to explain a phenomenon. Related to Ockham’s Razor.

French mathematician, physicist, and philosopher born in Clermont, France (1623 – 1662 CE). Pascal made contributions toward the development of mechanical calculators and the study of fluids and pressure. His writings contributed to the development of the scientific method; and along with Pierre de Fermat he laid the foundations of probability theory which led to development of statistical methods. For further information see Blaise Pascal; also see our module Data: Statistics.

Used in the following modules: Data: Statistics

A French chemist and biologist, born in Dole, France (1822-1895). Pasteur founded the science of microbiology and proved that microorganisms cause most infectious diseases. He also invented the process of pasteurization, made significant contributions to the science of brewing and winemaking, and developed vaccines for rabies and anthrax. For further information see Louis Pasteur.

Used in the following modules: DNA I, Research Methods: Experimentation, Research Methods: The Practice of Science, Scientists and the Scientific Community

English statistician and geneticist born in London, England (1857-1936). Pearson is credited with establishing the field of mathematical statistics. His landmark book Grammar of Science discussed the importance that probability and correlation have in scientific research, and had a profound impact on many scientists including Albert Einstein. He refined the statistical concept of correlation and introduced the concepts of regression and the chi-square test. For further information, see Karl Pearson.

Used in the following modules: Data: Uncertainty, Error, and Confidence, Research Methods: The Practice of Science

The process of subjecting scholarly work, research or ideas to the scrutiny of others who are experts in the same field. For further information see: Peer Review.

Used in the following modules: Data: Analysis and Interpretation, Scientific Communication: Peer Review, Scientific Communication: Understanding Scientific Journals and Articles, Scientific Communication: Utilizing the Scientific Literature, Scientific Ethics, Scientific Institutions and Societies, Scientists and the Scientific Community

A short polymer (~2-10 units) of amino acids.

Used in the following modules: Fats and Proteins

A rock composed primarily of the mineral olivine. The high percentage of iron and magnesium in olivine creates a very dense rock. Peridotite is the main rock within the mantle.

Used in the following modules: Earth Structure

A symbol representing a measure of the effective concentration of hydrogen ions in a solution, pH = -log [H⁺]. pH is a measure of the acidity (or basicity) of a solution, where values of 0 to 14 are possible. Acid solutions have a pH < 7, basic solutions have pH > 7, neutral solutions have pH = 7.

Used in the following modules: Absorption, Distribution and Storage of Chemicals, Acids and Bases, Scientific Ethics, Scientists and the Scientific Community

The appearance of a specific characteristic in an organism as determined by its genotype.

Used in the following modules: Genetics I, Genetics II

A lipid or glyceride that contains a phosphate group. The phosphate group imparts a polar side to the molecule, while the lipid end remains relatively non-polar. Phospholipids are the main form of lipid in cell membranes.

Used in the following modules: Absorption, Distribution and Storage of Chemicals, Cells

Formation of carbohydrates from carbon dioxide and a source of hydrogen (as water) in the chlorophyll-containing tissues of plants exposed to light.

Used in the following modules: Carbohydrates, Cells, Light II, The Carbon Cycle

see photosynthesis.

Used in the following modules: Earth's Atmosphere

A place where two or more tectonic plates meet and interact. Plate boundaries can be convergent, divergent, or transform boundaries, depending on which direction the plates are moving.

Used in the following modules: Plate Tectonics II, The Rock Cycle

A covalent bond in which electrons are unequally shared between bonding atoms. A polar covalent bond is formed when one atom participating has a stronger affinity for electrons, or electronegativity, than its bonding partner. A polar bond will result in an equal distribution of electron charge across the bonding pair. Compare to non-polar covalent bond, polar molecule.

Used in the following modules: Chemical Bonding

A molecule that has an unequal distribution of bonding electrons, which results in an asymmetrical electrical charge (or dipole) across the molecule. Polar molecules are formed when polar covalent bonds are oriented so that the molecule contains a partially charged positive end and negative end. As a result of the uneven electrical charge, polar molecules are commonly attracted to each other by dipole-dipole interactions. Polar molecules often dissociate in water to form electrolytes. Polar molecules Compare to non-polar molecule, ionic compound.

Used in the following modules: Water

Refer to polar covalent molecule.

Used in the following modules: Absorption, Distribution and Storage of Chemicals

The directionality of a magnetic field, which consists of a north and south pole of equal and opposite strength. Lines of magnetic force emanate from the north pole and terminate at the south pole. When the earth’s magnetic north pole corresponds with the geographic north pole (as it does now), the polarity of the magnetic field is normal; when the magnetic north pole corresponds with the geographic south pole, the polarity of the field is reversed.

Used in the following modules: Plate Tectonics I

Gamete of a flowering plant, similar to sperm cells in mammalian organisms.

Used in the following modules: Genetics I

A large molecule consisting of recurring units of a smaller molecule. A polymer can be thought of as a molecular chain, in which small molecules called monomers form the links.

Used in the following modules: Carbohydrates, DNA I, DNA II, DNA III, Fats and Proteins, Minerals III, Scientific Institutions and Societies

In science, a positive control refers to a system that is exposed to a treatment with a known effect. Thus, the positive control helps to establish that a response will occur, or provides a measure of the response of a variable to a known treatment. For more information, see: Research Methods: Experimentation

Used in the following modules: Research Methods: Experimentation

The energy an object possesses by virtue of its position in relation to a field of force. For example, lifting a mass m by h meters increases its potential energy by m·g·h, where g is the acceleration due to gravity.

Used in the following modules: Data: Using Graphs and Visual Data, Energy

A solid or otherwise insoluble product that is formed by a chemical reaction occuring in a liquid solution.

Used in the following modules: DNA III, The Carbon Cycle, The Rock Cycle

In science, precision refers to the degree of specified detail which can be expressed in a value. For example, a value expressed to three decimal places can be considered more precise than one made to two places. The determination of precision is a function of the degree to which individual measurements vary around a central value. Values with high precision are highly reproducible because repeated measurement will reliably give a similar result; however, they may or may not be accurate. Precision relates to the statistical error associated with a value. Compare to accuracy. See the module Uncertainty.

Used in the following modules: Data: Uncertainty, Error, and Confidence, Minerals II

Cleaning or grooming.

Used in the following modules: Adaptation

English chemist, natural philosopher and theologian, born in Yorkshire (1733-1804). He is most frequently noted for discovering oxygen. Priestly also isolated and characterized 7 additional gases, and his work furthered the scientific understanding of photosynthesis and respiration. For further information see Joseph Priestley.

Used in the following modules: Matter

The likelihood that a given event will occur. In statistics, probability is often expressed as a ratio of the number of actual occurrences of an event to the number of possible occurrences of the same event, i.e. there is a 50% probability of obtaining heads in a coin toss.

Used in the following modules: Data: Statistics, Data: Uncertainty, Error, and Confidence, Research Methods: Comparison, Research Methods: Experimentation, Research Methods: Modeling

The material that is formed as a result of a chemical reaction. Written on the right side of a chemical equation. Compare to reactant.

Used in the following modules: Chemical Equations, Data: Statistics, Data: Uncertainty, Error, and Confidence, Research Methods: Comparison, Research Methods: Modeling, The Carbon Cycle

In science, prospective research refers to the study of events moving forward in time. Generally this is done by designing a scientific study, and tracking, observing, or evaluating the course of events within that study as they occur. For more information, see: Research Methods: Comparison

Used in the following modules: Data: Statistics, Research Methods: Comparison

Macromolecules that are polymers of individual amino acids arranged in a chain and joined together by peptide bonds (and so also referred to as polypeptides). A minimum polymer length of approximately 40 amino acid units appears to be a functional size limit, and polymers shorter than this limit are commonly referred to as peptides. Proteins comprise approximately 50% of the dry weight of cells and fill a number of purposes, both functional and structural.

Used in the following modules: Absorption, Distribution and Storage of Chemicals, Carbohydrates, Cells, DNA I, DNA II, DNA III, Fats and Proteins, The Nitrogen Cycle

A sub-atomic (ß link to atom) particle with a positive charge of 1.60 × 10^-19 coulombs and a mass of 1.672 × 10^-27 kg. Protons are found in the nucleus of atoms. Compare to the electron, neutron.

Used in the following modules: Atomic Theory I, Atomic Theory II, Chemical Reactions, Nuclear Chemistry, Research Methods: Modeling, Teaching Effectively with Multimedia, The Mole, The Periodic Table of Elements

French chemist, born in Angers (1754-1826). Proust proposed that the proportions of substances that combine in a given reaction are always the same. This is now known as the Law of Definite Proportions or Proust’s Law. For further information, see Joseph Proust.

Used in the following modules: Matter

Greek mathematician and philosopher, born in Samos (ca. 569-475 BCE). Pythagoras is best known for his proof of the Pythagorean theorem, which states that the square of the hypotenuse of a right-triangle (c) is equal to the sum of the squares of the other two sides (a and b) such that a² + b² = c². He also founded a movement called Pythagoreanism, which held everything could be both predicted and explained by mathematics. For further information see Pythagoras

Used in the following modules: Research Methods: The Practice of Science, Waves and Wave Motion