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8th grade · Science · Unit 11 of 11

Clues from Embryos

Similar embryos and body structures show how species are related.

What your child practices

Practices comparing pictures and descriptions of embryos across species (tails and gill-like folds in fish, chicks and people) and structures with the same origin, like a bat's wing and a human arm, to find relationships that are hard to see in the adult animals.

New York State Learning Standards learning standard: MS-LS4-3; MS-LS4-2 · patterns of similarity in embryos and in body structures that show how species are related

How we explain it

Children can open this short lesson before they practice.

  1. Early embryos of fish, birds and mammals look very alike, with tails and gill-like folds.
  2. Scientists compare embryos at matching stages to look for patterns.
  3. Vestigial parts, like the human tailbone, have little use now but hint at ancestors.

Example: The human tailbone has little use. What is a part like this called? It is a small leftover structure. Answer: vestigial

Clues from Embryos in New York

In the New York State Learning Standards, this is unit 11 of 11 in 8th grade Science, after Digital & Analog Signals.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: New York State Education Department (NYSED)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Embryos can show relationships that are not easy to see in…

    • early development
    • pictures of embryos
    • the adult animals
    • the embryos

  2. Question 2

    Adult barnacles look like clams stuck to rocks, but their larvae look like…

    • young fish
    • insect eggs
    • young shrimp and crabs
    • plant seeds

  3. Question 3

    Early vertebrate embryos have folds near the throat. In fish, these become…

    • hair
    • gills
    • wings
    • lungs

  4. Question 4

    In humans, the same throat folds become parts of the…

    • knees
    • feet
    • hair
    • ears, jaw and throat

  5. Question 5

    A whale's flipper and a human hand have…

    • the same size
    • no bones
    • the same skin
    • similar bones

  6. Question 6

    Why do scientists compare the embryos of many species, not just two?

    • Patterns across many species give stronger evidence
    • Two is always enough
    • All embryos are identical
    • It is faster

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