At the end of the school year, there are certain conceptual understandings that we want our students to have. Achieving these learning goals lays the groundwork for more sophisticated understandings as students proceed through their learning experiences. The Understanding Evolution Conceptual Framework is an effective tool for identifying a sequence of age-appropriate conceptual understandings (K-16) to guide your teaching.

The conceptual framework is aligned with the 2012 Framework for K-12 Science Education and the Next Generation Science Standards (NGSS). In the concepts below, conceptual alignment is indicated by a code that follows each aligned concept. For example, LS4.A indicates correspondence to the Life Sciences core idea “Evidence of common ancestry and diversity” from both the NGSS and the Framework for grades 3-5, P3 indicates correspondence to “Planning and carrying out investigations,” the third of eight Science and Engineering Practices listed in those documents, and NOS2 indicates correspondence to the second concept outlined in NGSS’s appendix on the nature of science, “Scientific knowledge is based on empirical evidence.” Read more about Understanding Evolution and the NGSS/Framework alignment.

The Understanding Evolution Framework is divided into five strands, and a selection of teaching resources (i.e., lessons, activities, readers, and interactive online modules) targeting most concepts has been identified.

Jump to: History of Life | Evidence of Evolution | Mechanisms of Evolution | Nature of Science | Studying Evolution

History of Life concepts for 9-12

1. Biological evolution accounts for diversity over long periods of time. LS4.A, LS4.D (See Lessons)
   1. Through billions of years of evolution, life forms have continued to diversify in a branching pattern, from single-celled ancestors to the diversity of life on Earth today. (See Lessons)
   2. Life forms of the past were in some ways very different from living forms of today, but in other ways very similar. LS4.A (See Lessons)
2. Present-day species evolved from earlier species; the relatedness of organisms is the result of common ancestry. LS4.A (See Lessons)
   1. Life on Earth 3.8 billion years ago consisted of one-celled organisms similar to present-day bacteria. (See Lessons)
   2. There is evidence of eukaryotes in the fossil record from about one billion years ago; some were the precursors of multicellular organisms.
   3. The early evolutionary process of eukaryotes included the merging of prokaryote cells. (See Lessons)
3. Geological change and biological evolution are linked. (See Lessons)
   1. Tectonic plate movement has affected the evolution and distribution of living things. ESS1.C (See Lessons)
   2. Living things have had a major influence on the composition of the atmosphere and on the surface of the planet. ESS2.E (See Lessons)
4. During the course of evolution, only a small percentage of species have survived until today. (See Lessons)
   1. Background extinctions are a normal occurrence. (See Lessons)
   2. Rates of extinction vary. (See Lessons)
   3. Mass extinctions occur. (See Lessons)
   4. Extinction can result from environmental change. (See Lessons)
   5. Extinctions may create opportunities for further evolution in other lineages to occur.
5. Rates of evolution vary. (See Lessons)
   1. Rates of speciation vary. (See Lessons)
   2. Evolutionary change can sometimes happen rapidly. (See Lessons)
   3. Some lineages remain relatively unchanged for long periods of time. (See Lessons)

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Evidence of Evolution concepts for 9-12

1. The patterns of life’s diversity through time provide evidence of evolution. (See Lessons)
2. An organism’s features reflect its evolutionary history. (See Lessons)
   1. There is a fit between organisms and their environments, though not always a perfect fit. LS4.C (See Lessons)
   2. There is a fit between the form of a trait and its function, though not always a perfect fit. (See Lessons)
   3. Some traits of organisms are not adaptive. (See Lessons)
   4. Features sometimes acquire new functions through natural selection. (See Lessons)
3. The fossil record provides evidence for evolution. (See Lessons)
   1. The fossil record documents the biodiversity of the past. (See Lessons)
   2. The fossil record contains organisms with transitional features. (See Lessons)
   3. The fossil record documents patterns of extinction and the appearance of new forms. (See Lessons)
   4. The sequence of forms in the fossil record is reflected in the sequence of the rock layers in which they are found and indicates the order in which they evolved. (See Lessons)
   5. Radiometric dating can often be used to determine the age of fossils. (See Lessons)
4. There are similarities and differences among fossils and living organisms. (See Lessons)
5. Similarities among existing organisms provide evidence for evolution. LS4.A (See Lessons)
   1. Anatomical similarities of living things reflect common ancestry. LS4.A (See Lessons)
   2. There are similarities in the cell function of all organisms. LS4.A (See Lessons)
   3. All life forms use the same basic DNA building blocks. LS4.A (See Lessons)
   4. Developmental similarities of living things often reflect their relatedness. LS4.A (See Lessons)
   5. Not all similar traits are homologous; some are the result of convergent evolution. (See Lessons)
6. Artificial selection provides a model for natural selection. (See Lessons)
   1. People selectively breed domesticated plants and animals to produce offspring with preferred characteristics. (See Lessons)

To help you teach these concepts, you may want to explore Lines of Evidence or Adaptation.

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Mechanisms of Evolution concepts for 9-12

1. Evolution occurs through multiple mechanisms.
   1. Evolution results from selection acting upon genetic variation within a population. LS4.B (See Lessons)
   2. Evolution results from genetic drift acting upon genetic variation within a population. (See Lessons)
2. There is variation within a population. LS3.B (See Lessons)
   1. Natural selection acts on the variation that exists in a population. LS4.B, LS4.C (See Lessons)
   2. Natural selection acts on phenotype as an expression of genotype. (See Lessons)
   3. The amount of genetic variation within a population may affect the likelihood of survival of the population; the less the available diversity, the less likely the population will be able to survive environmental change. (See Lessons)
3. New heritable traits can result from recombinations of existing genes or from genetic mutations in reproductive cells. LS3.B (See Lessons)
   1. Mutations are random. (See Lessons)
   2. Organisms cannot intentionally produce adaptive mutations in response to environmental influences. (See Lessons)
   3. Complex structures may be produced incrementally by the accumulation of smaller useful mutations. (See Lessons)
4. Inherited characteristics affect the likelihood of an organism’s survival and reproduction. LS4.B, LS4.C (See Lessons)
   1. Over time, the proportion of individuals with advantageous characteristics may increase (and the proportion with disadvantageous characteristics may decrease) due to their likelihood of surviving and reproducing. LS4.B, LS4.C (See Lessons)
   2. Populations, not individuals, evolve. (See Lessons)
   3. Traits that confer an advantage may persist in the population and are called adaptations. LS4.B, LS4.C (See Lessons)
   4. The number of offspring that survive to reproduce successfully is limited by environmental factors. LS4.B, LS4.C (See Lessons)
   5. Depending on environmental conditions, inherited characteristics may be advantageous, neutral, or detrimental. (See Lessons)
   6. Environmental changes may provide opportunities that can influence natural selection. LS4.B, LS4.C (See Lessons)
5. Fitness is reproductive success — the number of viable offspring produced by an individual in comparison to other individuals in a population/species. (See Lessons)
   1. Fitness is often measured using proxies like mass, number of matings, and survival because it is difficult to measure reproductive success directly.
6. Random factors can affect the survival of individuals and of populations. (See Lessons)
7. Speciation is the splitting of one ancestral lineage into two or more descendent lineages. (See Lessons)
   1. Speciation is often the result of geographic isolation. (See Lessons)
   2. Speciation requires reproductive isolation. (See Lessons)
   3. Occupying new environments can provide new selection pressures and new opportunities, leading to speciation. LS4.C (See Lessons)
8. Evolution does not consist of progress in any particular direction. (See Lessons)

To help you teach these concepts, you may want to explore Mechanisms of Evolution, Speciation, or Misconceptions about How Evolution Works.

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Nature of Science concepts for 9-12

1. Science focuses on natural phenomena and processes. (See Lessons)
2. Scientific knowledge is open to question and revision as we come up with new ideas and discover new evidence. P4, P6, NOS3 (See Lessons)
3. A hallmark of science is exposing ideas to testing. P3, P4, P6, P7 (See Lessons)
   1. Scientists test their ideas using multiple lines of evidence. P6, NOS2 (See Lessons)
   2. Scientists use multiple research methods (experiments, observational research, comparative research, and modeling) to collect data. P2, P3, P4, NOS1 (See Lessons)
   3. Scientists can test ideas about events and processes long past, very distant, and not directly observable. (See Lessons)
4. Scientists may explore many different hypotheses to explain their observations. P7 (See Lessons)
5. The real process of science is complex, iterative, and can take many different paths. (See Lessons)
6. Accepted scientific theories are not tenuous; they must survive rigorous testing and be supported by multiple lines of evidence to be accepted. NOS2, NOS4 (See Lessons)
7. Science is a human endeavor. NOS7 (See Lessons)
8. Authentic scientific controversy and debate within the community contribute to scientific progress. P7 (See Lessons)

To help you teach these concepts, you may want to explore Nature of Science.

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Studying Evolution concepts for 9-12

1. Our knowledge of the evolution of living things is always being refined as we gather more evidence. (See Lessons)
2. Our understanding of life through time is based upon multiple lines of evidence. (See Lessons)
   1. Scientists use the similarity of DNA nucleotide sequences to infer the relatedness of taxa. LS4.A (See Lessons)
   2. Scientists use anatomical evidence to infer the relatedness of taxa. LS4.A (See Lessons)
   3. Scientists use developmental evidence to infer the relatedness of taxa. LS4.A (See Lessons)
   4. Scientists use fossils (including sequences of fossils showing gradual change over time) to learn about past life. (See Lessons)
   5. Scientists use physical, chemical, and geological evidence to establish the age of fossils. (See Lessons)
   6. Scientists use the geographic distribution of fossils and living things to learn about the history of life. (See Lessons)
   7. Scientists use experimental evidence to study evolutionary processes. (See Lessons)
   8. Scientists use artificial selection as a model to learn about natural selection. P2 (See Lessons)
3. Classification is based on evolutionary relationships. (See Lessons)
   1. Evolutionary trees (i.e., phylogenies or cladograms) portray hypotheses about evolutionary relationships. (See Lessons)
   2. Evolutionary trees (i.e., phylogenies or cladograms) are built from multiple lines of evidence. (See Lessons)
4. As with other scientific disciplines, evolutionary biology has applications that factor into everyday life. (See Lessons)

To help you teach these concepts, you may want to explore Lines of Evidence, History of Evolutionary Thought, or Tree Building.

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