Grade 8Science

Focus: In this unit, students investigate the phenomenon of the similarities and differences between organisms. In doing so they ask and resolve questions about phenotypes, genotypes, and inheritance in both sexually and asexually reproducing organisms The subtitle of this unit is Why are living things different from one another? Phenomena such as the different levels of musculature in cattle, variation within tulips, different phenotypes of planaria are things students might have observed, but what causes these differences? What is the genetic basis for variation among organisms? What are genes and alleles? This unit allows students to observe the phenomenon of variation and inheritance and then spend time working with classmates to analyze the shared experience, formulate new questions, and developing new strategies for answering them. Students explore concepts that include the following:

  • How do organisms get their differences?
  • How do diet and exercise affect muscle size?
  • How does an animal get extra-big muscles?
  • How can we use our model to explain a different trait variation?
  • How do plants reproduce?
  • How do organisms reproduce without sperm and eggs?
  • How much of trait variation in a population is controlled by genes or by the environment?

As students move through their day-to-day activities, they will also read Core Knowledge literacy selections. These include factual articles, history of the sciences, art and literature, spotting bad science in the media and advertisements, graphics comprehension, research-type articles, reliability of sources, and other areas of science literacy.

Lesson Numbers:

  • Teacher Guide: 17 Lessons
  • Student Reader: 5 Collections

Lesson time:

  • Lessons can be completed in one or more class periods.
  • A Pacing Guide, found in Online Resources, offers the suggestion that the entire unit should take about 28 days if class is held each day.
  • A complete list of materials needed to complete the unit is also provided in the Online Resources.
  • The Core Knowledge Student Reader includes on reading collection per week for every week of the unit. A week’s reading collection relates to the lessons completed in the previous week.
    • The reading is assigned at the beginning of the week with the accompanying writing exercise due at the end of the week.
    • The reading and writing exercises are designed to be completed by students independently with brief, supporting, teacher-facilitated discussions at the beginning, midpoint, and end of the week.

Additional Search Terms for the Student Reader:

• science literacy • genetics • gene • environment • variation • trait • phenotype • genotype • twins • karyotype • DNA • allele • gene pool • selective breeding • genetic diversity • sexual reproduction • asexual reproduction • pollination • clone • epigenetic • nonfiction • informational text

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