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9th grade · Science · Unit 18 of 28

Earth's Early History

How Earth formed, and how life and Earth changed each other.

What your child practices

Practices using evidence from meteorites, moon rocks and Earth's oldest minerals to describe how Earth formed about 4.6 billion years ago, and how living things and Earth's systems changed each other, from early microbes adding oxygen to the air to plants building soil.

New York State Learning Standards learning standard: HS-ESS1-6; HS-ESS2-7 · evidence of Earth's formation and early history, and how Earth's systems and life have changed each other

How we explain it

Children can open this short lesson before they practice.

  1. Earth formed about 4.6 billion years ago. Meteorites, moon rocks and old minerals show this.
  2. Oceans formed when water vapor cooled and fell as rain.
  3. Life changed Earth: oxygen built up, the ozone layer blocked UV, and land plants built soil.

Example: How did the ozone layer help life move onto land? Ultraviolet light harms living things. Ozone blocks much of it. Answer: it blocked harmful UV light

Earth's Early History in New York

In the New York State Learning Standards, this is unit 18 of 28 in 9th grade Science, after Plate Tectonics and before Air Masses & Fronts.

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

    Earth's oceans formed when water vapor from volcanoes and impacts…

    • escaped into space
    • cooled and condensed into rain
    • turned into oxygen
    • froze into rock

  2. Question 2

    Banded iron formations formed when oxygen made by early microbes…

    • formed the moon
    • reacted with iron dissolved in the oceans
    • melted the crust
    • froze the oceans

  3. Question 3

    Stromatolites are layered rock mounds built by…

    • colonies of microbes
    • dinosaurs
    • volcanoes
    • glaciers

  4. Question 4

    The moon is covered in craters but Earth has few because Earth…

    • was never hit
    • is made of ice
    • has no gravity
    • has weathering, erosion and moving plates that erase them

  5. Question 5

    Most scientists think the moon formed when…

    • a large object collided with the young Earth
    • the sun threw off a piece
    • Earth split in half on its own
    • a comet froze

  6. Question 6

    Over millions of years, Earth's climate warmed or cooled partly as living things…

    • changed the sun's color
    • stopped plate motion
    • changed the moon's orbit
    • added or removed carbon dioxide from the air

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