Grades 6–8. In this unit students answer the question, "Why are living things different from one another?" Cattle with differences in musculature introduce students to the topic of trait variations in living things, which leads to an exploration of genetic and environmental factors in those variations. Kit includes basic teacher access to instructional materials on CarolinaScienceOnline.com, plus enough materials to teach 1 class of 32 students per day.

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Grades 6–8. In Unit 8.5 Genetics, Carolina Certified Version*, students work to answer the Unit Driving Question: "Why are living things different from one another?"

This unit on genetics starts out with students noticing and wondering about photos of two cattle, one of which has significantly more muscle than the other. The students then observe photos of other animals with similar differences in musculature: dogs, fish, rabbits, and mice. After developing initial models for the possible causes of these differences in musculature, students explore a collection of photos showing a range of visible differences. Students gather other examples of trait variation they've seen in their lives and share them with the class. The photos they've seen and discussions they've had about trait variation spark questions and ideas for investigations generally around why there are differences among living things, and specifically around the causes of these extra-big muscles.

In the first lesson set, students use videos, photos, data sets, and readings to investigate what causes an animal to get extra-big muscles. Students figure out how muscles typically develop as a result of environmental factors such as exercise and diet. Then students work with cattle pedigrees, including data about chromosomes and proteins, to figure out genetic factors that influence the heavily muscled phenotype. Students obtain information from their readings that the MSTN gene causes the myostatin protein, which impacts muscle growth. From there, students explore selective breeding in cattle. In the second lesson set, students use what they've learned from explaining cattle musculature to help them explain other trait variations they've seen. They investigate plant reproduction, including selective breeding and asexual reproduction (in plants and other organisms) and other examples of traits that are influenced by genetic and environmental factors. Students figure out that environmental and genetic factors together play a role in the differences among living things.

Through these investigations, students:

• Obtain, evaluate, and communicate information about muscle substructure, the influence of exercise on muscle development, the function of the myostatin protein, selective breeding, examples of asexual reproduction, and how different traits are influenced by environmental and genetic factors.
• Use mathematics and computational thinking to find the probability of offspring with certain genotypes from parents with certain genotypes.
• Develop and use a model to explain how genes provide instructions to rearrange building blocks from food into proteins, which then influence phenotypes.
• Construct an explanation for how specialized plant structures support sexual and asexual reproduction in plants.
• Develop and use a model to explain that environmental and genetic factors both influence trait variations in different amounts, depending on the specific situation.

This 1-Class Unit Kit includes basic teacher access to instructional materials on CarolinaScienceOnline.com, plus the materials needed to teach 1 class of 32 students per day.

Building Toward NGSS Performance Expectations

• MS-LS1-2: Develop and use a model to describe the function of a cell as a whole and ways the parts of cells contribute to the function.
• MS-LS1-4: Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants respectively.
• MS-LS1-5: Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms.
• MS-LS3-1: Develop and use a model to describe why structural changes to genes (mutations) located on chromosomes may affect proteins and may result in harmful, beneficial, or neutral effects to the structure and function of the organism.
• MS-LS3-2: Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.
• MS-LS4-5: Gather and synthesize information about the technologies that have changed the way humans influence the inheritance of desired traits in organisms.

Focal Science and Engineering Practices

• Obtaining, Evaluating, and Communicating Information
• Using Mathematics and Computational Thinking
• Developing and Using Models

The following practices are also key to the sensemaking in the unit:

• Asking Questions and Defining Problems
• Planning and Carrying Out Investigations
• Constructing Explanations and Designing Solutions

Focal Disciplinary Core Ideas

• LS1.A
• LS1.B
• LS3.A
• LS3.B
• LS4.B

Focal Crosscutting Concepts

• Cause and Effect
• Structure and Function

The following crosscutting concept is also key to the sensemaking in the unit:

• Patterns
• Scale, Proportion, and Quantity

*All enhancements to materials and instruction for this Carolina Certified Version of the unit are approved by OpenSciEd to preserve the integrity of the storyline and the instructional model.