MiddleSchoolPortal/ENCdl Science Subject List

From NSDLWiki

In 2002, the Eisenhower National Clearinghouse began the development of a K-12 science education subject thesaurus based on the concepts and terms used in the National Science Education Standards (NSES) (National Research Council, 1996). The goal of the NSF-funded project was to create a standard metadata classification system for digital library collections that would apply to K-12 science education learning objects. The NSES and the Benchmarks for Science Literacy (Rutherford, 1994) were chosen as foundational documents because the language within them would have meaning and relevance for teachers across the country. The ENCdl Science Subject List is a working vocabulary that is scientifically correct, reflects the NSES, and will serve the resource discovery needs of K-12 science educators.


National Research Council. (1996). National Science Education Standards. Washington, DC: National Science Foundation.

Rutherford, F.J. (1994). Benchmarks for Science Literacy. Cary, NC: Oxford University Press.

Subject Terms, Level 0 Subject Terms, Level 1 Subject Terms, Level 2 Scope Notes Equivalent and/or Related Terms
Earth and space science Use this subject strand for material with hard science content. Use History and Nature of Science strand for scientific breakthroughs. Use Personal and Social Issues strand for resources about humans and the environment (e.g., resources about pollution).
Climate Weather is short term. Climate refers to weather trends over a long period of time for a given region or place.
Global climate change Can be natural or human-induced and includes past, present, and future change. Includes but is broader than global warming: there has been and can be cooling. Climate change can involve more than temperature change. Climatic change, Global warming
Biogeochemical cycles Examples include the nitrogen cycle, carbon cycle, phosphorus cycle, and the sulfur cycle. Use Water cycle for resources specific to that cycle. Geochemical cycles, Nitrogen cycle, Carbon cycle, Phosphorus cycle, Sulfur cycle
Rock cycle
Water cycle Hydrologic cycle
Earth in the solar system
Earth's revolution Includes the relationship between one revolution of the Earth and one year.
Earth's rotation Includes how the rotation of the Earth relates to day and night.
Moon For resources about Earth's moon.
Seasons Includes why seasons occur, i.e., the tilt of the Earth's rotational axis and the Earth's orbit around the sun.
Sun For resources about Earth's sun.
Tides For materials about why tides occur, what the different types of tides are, and the effects they have.
Earth materials Includes uses of Earth materials.
Air Includes gases of the atmosphere. The context here is air as an Earth material with properties that make it useful. Use Atmosphere under Earth System Structure when resources refer to the entire layer (envelope) of gases that surround Earth.
Minerals Includes the physical and chemical properties of minerals and the usefulness of minerals.
Rocks Includes the physical and chemical properties of rocks and the usefulness of rocks.
Soil Includes the physical and chemical properties of soil and soil's usefulness.
Water Includes the physical and chemical properties of water, water chemistry, and water's uses. Use Earth system structure/Hydrosphere if a resource is primarily about water on a global scale. Use Earth's water for resources about particular bodies of water.
Earth processes
Crustal deformation Alterations of the shape and/or volume of rock that result when a body of rock is subjected to stress. Examples include the folding and faulting of rocks. Remember that there is oceanic crust. Folding, Folds, Faulting, Faults, Rock deformation
Earthquakes Seismology (ERIC uses this term)
Mountain building
Plate tectonics Branch of geophysics and seismology concerned with continental movements, based on the theory that the earth's surface is composed of vast crustal blocks that float across the mantle, with seismic activity and volcanism occurring primarily along the periphery of these blocks. (ERIC) Lithospheric plate movements, Tectonic plates
Sediment deposition Sedimentation
Volcanoes Physical geography (ERIC uses this term)
Earth system structure
Atmosphere If resources are about the envelope of gases that surround Earth, use this term. If resources are about air in general or about specific gases that living creatures use in particular ways, assign Earth materials/Air.
Hydrosphere Use for resources about water on a global scale. See Scope Note for Earth's water for instructions on cataloging other flavors of water.
Ozone layer Does not refer to low level/ground level ozone.
Earth's water Is about types of water and specific bodies of water. Also see Earth materials/Water (water as a useful resource and water's properties); Earth system structure/Hydrosphere (global water system); Cycles/Water cycle; and Earth in the solar system/Tides.
Freshwater Use for rivers, streams, lakes, ponds, creeks, groundwater, etc.
Oceans Saltwater
Energy sources Includes external and internal energy sources in the Earth system. The sun is an example of an external source, while radioactive decay is an internal source.
Energy transfer Conduction, convection, and radiation. Examples include the transfer of the sun's energy to Earth and convection in the mantle, in the oceans, and in the atmosphere. Conduction, Convection, Radiation
Fuels Energy resources used by humans including fossil fuels. Fossil fuels
Evolution Includes fossils as evidence of evolution.
Biological evolution Use for resources about biological evolution as it pertains to Earth or space or for resources about what scientists can learn from fossils, geologic evidence, etc. about how life evolved. Life Science/Evolution is for life science resources.
Earth system evolution
Geologic time
Solar system origin
Stellar evolution Star evolution, Life cycle of stars
Universe origin Cosmology
Solar system Astronomy (ERIC uses this term)
Meteoroids Use for meteoroid, the rocky object in space; meteor, the light from a falling meteoroid; and meteorite, remains of a meteoroid found on Earth. Meteor, Meteorite
Moons Use for moons of planets other than Earth. The Earth's moon is listed under Earth in the solar system.
Suns Use for the suns of planets other than Earth. Earth's sun is listed under Earth in the solar system.
Solar system changes Do not use for Earth changes. See Earth in the solar system for terms specific to Earth.
Phases of the moon Lunar phases, Moon’s phases, Moon phases
Space exploration Includes explorations of space made from Earth using, for example, optical or radio telescopes. Also includes explorations conducted in space such as those performed during manned space missions or by the Mars rovers.
Weather Weather is short term. Climate refers to weather trends over a long period of time for a given region or place.
Precipitation Includes different types of precipitation such as rain, snow, and sleet.
Storms Use Hurricanes or Tornadoes for resources about those specific types of severe storms.
Temperature As a weather metric/measure of the weather.
Wind Includes wind speed and direction.
History and nature of science
Historical perspectives This could be used with Scientific Breakthroughs.
Scientific breakthroughs
Scientists and inventors
Scientific enterprises
Fields of science This includes areas of study such as genetics or optics. The vocations related to these areas of study would go under careers.
Life science Biology
Animals Eukarya
Amphibians Frogs, Toads, Salamanders
Annelids Earthworms, Leeches, Marine polychaetes
Arthropods Crustaceans, Arachnids, Insects
Birds Aves
Boney fish Osteichthyes
Cartilagenous fish Chondrichthyes, Sharks, Rays
Cnidarians Corals, Jellyfish, Hydra
Dinosaurs Paleontology (ERIC uses this term)
Echinoderms Starfish, Sea urchins, Sand dollars, Sea Cucumbers, Brittle stars
Flat worms Platyhelminthes, Planaria, Tapeworms, Flukes, Trematode, Cestode
Jawless fish Lampreys, Agnatha
Mammals Marsupials, Monotremes, Placentals
Mollusks Clams, Squid, Octapus, Snails, Slugs, Nudibranchs
Reptiles Snakes, Lizards
Round worms Nematodes
Sponges Porifera
Bacteria Eubacteria, Archaea, Blue Green Algae
Behavior Include behavior of all organisms, for example, plants, animals, protists – geotropism, phototropism, etc.
Cell respiration
Chemical reactions
Nucleic acids Genetics (ERIC uses this term)
Proteins This is focusing on the reactions between amino acids as proteins are produced, the categories of proteins, and the relationship between shape and protein function.
Biodiversity Includes resources about lack of or changes to biodiversity. If the resource includes the broad impact in terms of ecosystem and/or evolution, mark those terms as well. This could include extinction.
Biological classification
Cell Includes cell level events, such as mitosis.
Cellular specializations This includes cells that differentiate into specific kinds of cells, such as liver or xylem cells.
Cellular structures This includes all of the specific organelles, cell membrane, and cell wall. The functions of these organelles are also included here. Osmosis and permeability would go here because those are aspects of cell membrane function.
Diffusion Osmosis
Membrane transport Use Cellular structures for endocytosis and exocytosis, since those are functions of the Golgi and cell membrane. Limit this to things moving through the membrane using protein carriers. Active transport
Ecosystems Includes ecosystem interactions that affect biodiversity and extinction.
Energy transfer This includes biomass. This can be related to Food Web, but one or the other can be assigned by itself.
Food web This can be related to energy transfer, but one or the other can be assigned by itself. Food chain
Population dynamics
Trophic levels Autotrophs, Heterotrophs, Consumers, Producers, Decomposers
Evolution Includes evidence such as biogeography, biochemistry, genetics, and fossils. If biodiversity is part of the resource, include that term as well. If related to earth science, use Earth and Space/Evolution/Evolution of Life.
Natural selection
Fungi Eukarya
Genetics Includes inheritance, genes, and gene expression. Inheritance, Heredity
Protein synthesis This refers to the process of protein synthesis starting with the DNA going through transcription and translation. It makes the connection between the sequence of nitrogen bases on nucleic acids and the sequence of amino acids in proteins. Transcription, Translation
Growth and development This could include mitosis depending on the context. Mitosis might also be found under Cell or Reproduction.
Life cycles
Organ systems Body systems
Cardiovascular system
Digestive system
Endocrine system
Excretory system
Immune system
Integumentary system Skin
Muscular system
Nervous system
Reproductive system This refers to the organ system and does not necessarily refer to activities at the cellular level. It might include meiosis, depending on the context.
Respiratory system
Skeletal system
Plants Nucleated multicellular organisms that contain chlorophyll and have rigid cell walls -- some classifications include bacteria, unicellular algae, and/or fungi (Note: Use a more specific term if possible). (ERIC) Eukarya, Plants (Botany) (ERIC)
Protists Eukarya
Reproduction This is referring to reproduction as a characteristic of living things.
Asexual reproduction This could include reproduction as a characteristic of living things, types of asexual reproduction, and the process of mitosis as it results in asexual reproduction.
Sexual reproduction This includes the process of sexual reproduction as it relates to the characteristics of living things. It might include a discussion of meiosis.
Viruses Parasitic particles capable of independent metabolism and reproduction within living cells. (ERIC) Microbiology (used by ERIC)
Personal and social issues
Human population growth Includes population density, carrying capacity, limits, birth rate, death rate, emigration, and immigration.
Humans and the environment
Conservation Includes recycling, land management, resource management, sustainability, and impacts on biodiversity. Resource management, Land management
Environmental change Includes natural and human induced change; examples include natural disasters such as hurricanes, earthquakes, asteroid impacts, floods, and processes such as desertification, ozone depletion, oil spills, and waste disposal.
Nonrenewable resources
Renewable resources
Personal health Hygiene (used by ERIC)
Disease Illness, viruses, bacteria, awareness, control, prevention, cure, and transmission. Illness
Drugs Alcohol, tobacco, over the counter medications and drug use, addiction, abuse, and development. Alcohol, Tobacco
Family relationships Parents
Nutrition Food pyramid, food groups, nutritional requirements, vitamins
Peer pressure Pressure, either planned or unplanned, exerted by peers to influence personal behavior. (ERIC) Peer influence (used by ERIC)
Personal hygiene
Physical fitness Exercise, strength, and cardiovascular endurance. Exercise
Psychological health Mental health Mental health
Safety and security Includes prevention, safety rules, preventing abuse, avoiding injury and accidents, preparing for fires in the home, safety on the job, dealing with occupational hazards, and staying safe during an earthquake or other natural disaster. Safety rules
Self image Body image, self perception Body image
Sex Includes sexuality, sex education, and Sexually Transmitted Diseases (STDs). Sexuality, Sex education
Science and technological challenges in society Includes setting policy, informing the public, the funding of research, the reciprocal effects of science and society on each other, the reciprocal effects of technology and society, the limitations of science and technology, and risk assessment.
Physical science
Chemical reactions Combustion
Acid base reactions Titration
Conservation of mass
Ionic reactions
Oxidation reduction reactions Redox reactions
Reaction rates
Stoichiometry Study of the quantities of materials consumed and produced by chemical reactions. (ERIC)
Electromagnetic radiation
Energy Mechanical energy, Thermal energy
Conservation of energy
Energy transfer Moving the same type of energy from one place to another
Energy transformation
Kinetic energy
Potential energy
Forces and motion Circular motion, Harmonic motion, Mechanics
Electrical forces
Electromagnetic forces
Electrostatic forces
Magnetism Magnets
Newton’s laws of motion
Simple machines
Gas laws
Kinetic molecular theory Kinetic theory, Modular structure (used by ERIC)
Radiation Process of energy emission. (ERIC)
Temperature Climate (used by ERIC)
Light Only use this subject when cataloging a resource about visible light. Optics, Visible light
Nuclear reactions
Heavy elements Use when smaller elements are joined to form heavier elements.
Properties of materials
Acids and bases Indicators, Buffers, pH
Chemical changes Also known as chemical reactions, a substance is transformed into a chemically different substance.
Chemical properties Describes the way a substance may change or "react" to form other substances.
Physical changes A substance changes its physical appearance but not its basic identity. All changes of state (e.g. solid to liquid to gas) are physical changes.
Physical properties Properties we can measure without changing the basic identity of the substance; examples are solubility, malleability, ductility, etc.
Sound Science of sound -- includes the study of the transmission of sound through various media or in various enclosures. (ERIC) Acoustics (used by ERIC)
States of matter
Structure of matter
Atomic mass Atomic number
Atomic theory Nuclear physics (used by ERIC)
Atomic weight
Chemical formulas
Covalent bonds
Crystalline solids Salts
Electron configuration
Hydrogen bonds
Ionic bonds
Molecular geometry
Organic molecules
Periodic table
Polymers Plastics (used by ERIC)
Subatomic particles Protons, Electrons, Neutrons, Quarks, Gluons
Science and technology
Agricultural technology Farming technology
Biotechnology Application note: It's fine to also add health technology if the resource stresses the health application of the biotechnology. The same best practice also applies to agricultural technology.
Energy technology Study and/or application of energy transfer or generation processes. Power technology (used by ERIC)
Engineering technology
Environmental technology Can include resources about technologies for environmental protection or remediation.
Health technology Medicine, Medical technology
Information and communications technology Includes resources about technologies such as remote sensing, GIS, computers, the Internet, and telecommunications.
Materials and manufacturing Includes materials science. Materials science
Nature of science and technology Includes how science and technology influence each other and the similarities and differences between science and technology.
Space technology Astronautics, Space program, Space shuttle, Space station, Space flight
Technological design Use for resources about design and the design process.
Transportation technology Includes resources about airplanes and flight, trains, wheels, ships, automobiles, etc. Aeronautics, Aerodynamics, Aircraft
Science as inquiry
Science process skills Broadly transferable intellectual skills, appropriate to all scientific endeavors -- includes basic process skills (e.g., observing, inferring, measuring, communicating, classifying, predicting, using time-space relations, using numbers) and integrated process skills (e.g., controlling variables, defining operationally, formulating hypotheses, interpreting data, experimenting, formulating models). (ERIC)
Analyzing data Preparation of factual information items for dissemination or further treatment (includes compiling, verifying, ordering, classifying, and interpreting). (ERIC) Data analysis (used by ERIC and in Math Subject List)
Asking questions Method or process of seeking knowledge, understanding, or information. (ERIC) Inquiry (used by ERIC)

Ordering of related phenomena into categories, groups, families, or systems according to characteristics or attributes. (ERIC)||Classification (used by ERIC)

Collecting data Generating or bringing together information that has been systematically observed, recorded, organized, categorized, or defined in such a way that logical processing and inferences may occur. (ERIC) Data collection (used by ERIC, data analysis is the broader term)
Communicating Transmission and reception of signals or meanings through a system of symbols (codes, gestures, language, etc.) common to sender and receiver. (ERIC) Communication, Communication (Thought transfer) (used by ERIC)
Experimenting Designing experiments, Conducting experiments, Indentifying variables, Controlling variables, Experimentation, Experiments (used by ERIC)

Processes by which hypotheses are accepted or rejected. (ERIC) ||Hypothesis testing (used by ERIC)

Interpreting data

Explanation of the meaning, implications, or limitations of factual information. (ERIC) ||Data interpretation (used by ERIC)

Measuring Process of obtaining a numerical description of the extent to which persons, organizations, or things possess specified characteristics. (ERIC) Measurement (used by ERIC)
Observing Directed or intentional examination of persons, situations, or things to obtain information -- includes the quantified values by which observed facts are represented. (ERIC)Observation (used by ERIC)
Predicting Process or act of foretelling future events, conditions, outcomes, or trends on the basis of current information. (ERIC) Prediction (used by ERIC)
Scientific habits of mind Process of reasoning from premise to conclusion. (ERIC) Critical thinking, Skepticism, Logical thinking (used by ERIC)
Using mathematics Complex behaviors developed through practice in order to complete mathematical tasks (Note: Use for documents whose specific focus is on the acquisition and/or use of mathematics skills -- do not use as an automatic adjunct to "Mathematics Curriculum," "Mathematics Education," etc.) (ERIC) Mathematics skills (used by ERIC)
Using scientific equipment
Using technology


The ENCdl Science Subject List work was funded through NSF NSDL Grant Number DUE 128632, Developing a National Digital Library Science Metadata Schema, as a supplement to the National Digital Library for Undergraduate Science, Mathematics and Technology Education Teacher Preparation and Professional Development Digital Library Project, NSF NSDL Grant Number DUE 008534 and the Eisenhower National Clearinghouse, U.S. Department of Education, Contract No. RJ97071001. The ideas and opinions expressed here do not necessarily reflect the positions or policies of the National Science Foundation or the U.S. Department of Education.


The Ohio State University holds copyright on all original materials we publish but grants permission for materials to be reproduced or to be adapted and used by others under a Creative Commons 3.0 Share-Alike license. Please contact Kimberly Lightle if you plan on using this resource.

Please use the following format to credit OSU.

Reprinted/Modified from ENCdl science subject list, version 1.0. Retrieved [insert date], from NSDL Middle School Portal: ENCdl Science Subject List. Copyright The Ohio State University.