Topic: Plate Tectonics

Below is a list of key ideas related to Plate Tectonics. For each key idea, you will find a list of sub-ideas, a list of items, results from our field testing, and a list of student misconceptions. After clicking on a tab, click on it again to close the tab.

The outer layer of the earth – including the continents and the ocean basins - consists of separate plates.

Students are expected to know that:

  1. The rock layer beneath the surface of the earth is divided into massive sections of solid rock, called “plates.” The plates fit closely together such that all of the edges of a plate touch the plate next to it.
  2. Plates are miles thick.
  3. The continents and ocean basins are part of the plates. The exposed solid rock of mountains is an example of plate material that is visible when it is not covered by water, soil, or loose rock such as sand.
  4. There are about 12-15 very large plates, each of which encompasses large areas of the earth’s outer layer (e.g., an entire continent plus adjoining ocean floor, or a large part of an entire ocean basin). Together these very large plates make up most of the entire outer layer of the earth. The rest of the outer layer is made up some additional smaller plates.
  5. The boundaries of continents and oceans are not necessarily the same as the boundaries of plates. Some boundaries between plates are found on continents, some on ocean floors, and some in places where oceans and continents meet.

Boundaries:

  1. Students are not expected to know the terms bedrock, lithosphere, crust, or mantle.
  2. Students are not expected to know the names of specific plates, the size of the smaller plates, or how many small plates there are.
  3. Students are not expected to know that the term “plates” refers to the lithosphere, or that two components (crust and upper mantle) make up the plates.
  4. Students are not expected to know that the plates are not uniform in composition or thickness.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

PTM104

Earth's plates are located deep within the earth and are not exposed at the earth's surface (AAAS Project 2061, n.d.).

53%

52%

PTM013

Plates are feet thick (AAAS Project 2061, n.d.).

49%

43%

PTM011

Plates are made of melted rock (AAAS Project 2061, n.d.).

40%

39%

PTM078

Earth's plates are separated by empty gaps (AAAS Project 2061, n.d.).

29%

40%

PTM103

The solid rock of a cliff is not a part of a plate (AAAS Project 2061, n.d.).

31%

30%

PTM096

The earth has seven plates (AAAS Project 2061, n.d.).

31%

28%

PTM010

There is one continent on each plate (AAAS Project 2061, n.d.).

31%

28%

PTM005

Plates are arranged like a stack of layers in the earth. (Libarkin et al., 2005; Marques and Thomson, 1997; Ford and Taylor, 2006; AAAS Project 2061, n.d.).

28%

N/A

PTM101

Earth's plates are piled on top of each other (AAAS Project 2061, n.d.).

27%

29%

PTM094

Ocean basins are not part of earth's plates (AAAS Project 2061, n.d.).

25%

23%

PTM110

Continents sit on top of a layer of water, and the water is above a plate (AAAS Project 2061, n.d.).

25%

21%

PTM015

The earth has about one hundred plates (AAAS Project 2061, n.d.).

23%

22%

PTM105

Plate boundaries only occur where continents meet ocean basins (AAAS Project 2061, n.d.).

22%

24%

PTM109

Continents are on top of plates but are not part of plates (AAAS Project 2061, n.d.).

22%

24%

PTM099

Earth's plates are not in contact with each other (AAAS Project 2061, n.d.).

24%

20%

PTM095

Continents are not part of earth's plates (Ford and Taylor, 2006; AAAS Project 2061, n.d.).

20%

18%

PTM098

Earth's plates are separated from each other by oceans (AAAS Project 2061, n.d.).

15%

16%

PTM106

Plate boundaries are always found in the middle of ocean basins (AAAS Project 2061, n.d.).

16%

12%

PTM100

Earth's plates are surrounded by melted rock so that the plates are not touching each other (AAAS Project 2061, n.d.).

15%

11%

PTM108

Continents are next to plates but are not part of plates (AAAS Project 2061, n.d.).

12%

11%

PTM012

Plates are several inches thick (AAAS Project 2061, n.d.).

12%

10%

PTM107

Plate boundaries cannot occur within a continent (AAAS Project 2061, n.d.).

11%

9%

PTM102

Earth's plates are made of sand (AAAS Project 2061, n.d.).

10%

8%

PTM097

The earth has one very large plate (AAAS Project 2061, n.d.).

7%

7%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.

The earth's plates sit on a hot, slightly softened layer of the earth.

Students are expected to know that:

  1. Rocks can be solid, liquid, or in a slightly softened form.
  2. The layer beneath earth’s plates is made of rock that is hotter and less rigid than the plates.
  3. The layer beneath earth’s plates is just slightly softened (just as wax and metal become softened when heated but not yet melted).
  4. The layer beneath earth’s plates moves very slowly and in different directions in different locations around the earth.

Boundaries:

  1. Students are not expected to know that the layer beneath the plates is called the asthenosphere, or that this layer has the properties it does because of pressure being applied to it in addition to the high temperature inside the earth.
  2. Students are not expected to know that the asthenosphere is not uniform and that liquid magma flows through parts of the asthenosphere.
  3. Students are not expected to know how the earth behaves beneath this layer.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number

Knowledge Being Assessed

Grades
6–8

Grades
9–12

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PT017001

The layer beneath earth's plates slowly moves in different directions in different places around the earth.

47%

53%

PT018001

Rocks can be solid, liquid, or in a slightly softened form.

27%

31%

PT016001

The layer beneath earth's plates mostly consists of slightly softened rock.

17%

13%

The earth's plates move very slowly, pressing against one another in some places and pulling apart in other places.

Students are expected to know that:

  1. The earth’s plates move continuously and very slowly (several inches per year) along with the slightly softened layer of rock beneath them.
  2. The motion of the plates results in the motion of all things that are part of the plates (e.g., continents, ocean basins, mountain ranges) and all things that sit on top of the plates (e.g., soil, ocean sediment, living things, and buildings).
  3. Because the slow motion of plates is continuous, it can result in plates moving great distances across the surface of the earth over very long periods of time.
  4. The direction of motion is different for different plates, and the direction of motion of a plate can change over time so that where a plate once pushed into another plate, it can later pull away from that plate.
  5. Because different plates move in different directions, plates can press together, move away from each other, and move alongside (parallel to) each other.
  6. It is possible to measure the rate of motion and direction of motion of a plate.

Boundaries:

  1. Students are not expected to know the terms that describe the different ways plates interact with each other at plate boundaries (e.g., convergent, divergent, transform).
  2. Students are not expected to know the forces that act on plates to cause them to move in one direction or another or that plates do not always move as a uniform block (i.e., that different parts of a single plate can move at different rates and in different directions).
  3. Students are not expected to know how the rate of motion of plates is measured.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

PTM123

Continents only move inches over hundreds of years, not feet or miles (AAAS Project 2061, n.d.).

34%

39%

PTM084

Continents and ocean basins move, but so slowly that they will barely have moved after hundreds of years (AAAS Project 2061, n.d.).

34%

39%

PTM128

Earth's plates move by floating on a layer of melted rock (AAAS Project 2061, n.d.).

33%

38%

PTM127

Continents would only move inches over millions of years, not feet or miles (AAAS Project 2061, n.d.).

31%

33%

PTM083

Ocean basins do not move (AAAS Project 2061, n.d.).

29%

30%

PTM122

Ocean basins move separately from earth's plates (AAAS Project 2061, n.d.).

27%

25%

PTM032

Plates move when the layer below them temporarily melts and moves (AAAS Project 2061, n.d.).

22%

21%

PTM126

Continents move so slowly that even after millions of years the distance they moved cannot be measured (AAAS Project 2061, n.d.).

17%

17%

PTM117

Earth's plates move several feet per year (AAAS Project 2061, n.d.).

18%

14%

PTM124

Continents move miles over hundreds of years (AAAS Project 2061, n.d.).

19%

14%

PTM119

Continents move separately from earth's plates (AAAS Project 2061, n.d.).

15%

14%

PTM031

Continents do not move (Ford and Taylor, 2006; AAAS Project 2061, n.d.).

13%

10%

PTM118

Earth's plates move several miles per year (AAAS Project 2061, n.d.).

11%

10%

PTM125

A continent would not move at all over 100 years (AAAS Project 2061, n.d.).

10%

9%

PTM120

Continents moved in the past, but they are no longer moving (AAAS Project 2061, n.d.).

11%

5%

PTM121

Ocean basins moved in the past, but they are no longer moving (AAAS Project 2061, n.d.).

10%

6%

PTM082

Earth's plates do not move (AAAS Project 2061, n.d.).

8%

8%

PTM035

The plates do not move because they sit on a layer of solid rock (AAAS Project 2061, n.d.).

6%

5%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.

When continental plate material from one plate presses against another plate, the continental plate material is forced upward, forming mountains.

Students are expected to know that:

  1. Continental plate material makes up continents, oceanic plate material makes up ocean basins, and the top part of any plate can be made of either oceanic or continental plate material or continental plate material in some places and oceanic plate material in other places.
  2. Continental plate material is made of rock that is less dense and much thicker than oceanic plate material.
  3. When two plates press together, if one plate has plate material at its edge that is less dense than the edge of the other plate, the less dense plate material will crumple upward, creating a bend or fold in the plate material but not causing the plate to break into smaller pieces of rock. If the plate material is approximately the same density on both edges, the edges of both will crumple upward.
  4. When continental plate material from one plate presses against oceanic plate material from another plate, the continental plate material crumples up over the oceanic plate material.
  5. As continental plate material from one plate presses against continental plate material from another plate, the edges of both plates crumple up, creating a bend or fold in the plate material but not causing the plate to break into smaller pieces of rock.
  6. The result of a plate crumpling up is mountains, which are composed of the continental plate material that has been folded upward.
  7. The crumpling up of plate material reduces the area of the earth’s surface covered by a plate.
  8. New mountains have formed throughout earth’s history, and mountains continue to develop as plates move and press together.

Boundaries:

  1. Students are not expected to know that continental plate material from one plate can sink under other continental plate material from another plate.
  2. Students are not expected to know that when two plates press together, plate material breaks (e.g., faults occur) as well as bends.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

PTM146

Earth's plates cannot bend (AAAS Project 2061, n.d.).

50%

45%

PTM039

Mountains form by the piling up of pieces of rock (AAAS Project 2061, n.d.).

50%

45%

PTM140

Continental plate material is only pushed upward when it pushes into continental plate material on another plate (AAAS Project 2061, n.d.).

37%

35%

PTM133

When two plates push together and continental plate material is at the edge of both plates, one plate will stop moving and the edge of the other plate will be pushed upward (AAAS Project 2061, n.d.).

22%

23%

PTM142

When a plate with continental plate material at its edge pushes into another plate, the continental plate material is always pushed downward (AAAS Project 2061, n.d.).

15%

18%

PTM132

When two plates push together and continental plate material makes up the edge of both plates, both plates will be pushed downward (AAAS Project 2061, n.d.).

15%

13%

PTM144

New mountains developed in the past, but no new mountains are developing today (AAAS Project 2061, n.d.).

13%

12%

PTM145

There have been times when mountains have developed in the past, but only occasionally (i.e., not continuously) (AAAS Project 2061, n.d.).

14%

10%

PTM143

All mountains that exist today formed when the earth first formed (AAAS Project 2061, n.d.).

10%

7%

PTM130

When two plates push into each other, both plates will stop moving (AAAS Project 2061, n.d.).

9%

9%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.

When two plates are pulling apart, melted rock material rises up between the plates, creating new plate material.

Students are expected to know that:

  1. When two plates pull apart from each other, melted rock rises up between the plates.This rock solidifies as it cools, adding new oceanic plate material to the edges of both plates so that the plates are always in contact with each other and no space forms between them.
  2. The process of melted rock rising up between the plates can be gradual, with the melted rock material slowly welling up between the plates, and it can be sudden, with melted rock material suddenly projecting out from between the plates in volcanic eruptions.
  3. Melted rock can well up or erupt anywhere along the boundary where two plates are pulling apart.As the melted rock cools, it begins to form a row of mountains along the edges of both plates where they are pulling apart.
  4. When two plates move apart and split a continent in two, an ocean basin forms between them that widens over time.The ocean basin grows as new plate material is continuously added to the edge of the separating plates.
  5. At the same time that new plate material is being added as plates pull apart, other plate material is being folded upward or recycled into the interior of the earth so that the plate material that is lost in one place is balanced by the new plate material that is gained in another.

Boundaries:

  1. Students are not expected to know why some oceanic plate material is denser than other oceanic plate material.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number

Knowledge Being Assessed

Grades
6–8

Grades
9–12

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PT041001

New plate material forms where two plates pull apart.

47%

51%

PT033001

The amount of new plate material that is added to a plate is balanced by the amount of plate material that is pushed into the earth's interior or is crumpled upward.

41%

46%

PT032001

As two plates move apart new plate material forms between them.

27%

30%

When continental plate material from one plate presses against another plate, the continental plate material is forced upward, forming mountains.
-and-
When oceanic plate material from one plate presses against another plate, it can slide under the other plate, sinking deep into the earth.

These items have been aligned to more than one key idea. To view the sub-ideas click on a key idea below.

  • When continental plate material from one plate presses against another plate, the continental plate material is forced upward, forming mountains.

    Students are expected to know that:

    1. Continental plate material makes up continents, oceanic plate material makes up ocean basins, and the top part of any plate can be made of either oceanic or continental plate material or continental plate material in some places and oceanic plate material in other places.
    2. Continental plate material is made of rock that is less dense and much thicker than oceanic plate material.
    3. When two plates press together, if one plate has plate material at its edge that is less dense than the edge of the other plate, the less dense plate material will crumple upward, creating a bend or fold in the plate material but not causing the plate to break into smaller pieces of rock. If the plate material is approximately the same density on both edges, the edges of both will crumple upward.
    4. When continental plate material from one plate presses against oceanic plate material from another plate, the continental plate material crumples up over the oceanic plate material.
    5. As continental plate material from one plate presses against continental plate material from another plate, the edges of both plates crumple up, creating a bend or fold in the plate material but not causing the plate to break into smaller pieces of rock.
    6. The result of a plate crumpling up is mountains, which are composed of the continental plate material that has been folded upward.
    7. The crumpling up of plate material reduces the area of the earth’s surface covered by a plate.
    8. New mountains have formed throughout earth’s history, and mountains continue to develop as plates move and press together.

    Boundaries:

    1. Students are not expected to know that continental plate material from one plate can sink under other continental plate material from another plate.
    2. Students are not expected to know that when two plates press together, plate material breaks (e.g., faults occur) as well as bends.
  • When oceanic plate material from one plate presses against another plate, it can slide under the other plate, sinking deep into the earth.

    Students are expected to know that:

    1. Some oceanic plate material is denser than other oceanic plate material.
    2. When oceanic plate material from one plate presses against another plate that is less dense than it (made of continental or oceanic plate material), it will slide beneath the other plate toward the interior of the earth.
    3. The edge of the denser plate will continue to fall toward the interior of the earth as long as the two plates move toward each other.

    Boundaries:

    1. Students are not expected to know the term “subduction.”
    2. Students are not expected to know what makes some plate material denser than other plate material.
    3. Students are not expected to know that continental plate material sometimes can slide under continental plate material.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number

Knowledge Being Assessed

Grades
6–8

Grades
9–12

Select This Item for My Item Bank

PT027003

Oceanic plate material is pushed downward when it presses against continental plate material.

39%

46%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

PTM129

Continental plate material is pushed beneath oceanic plate material when two plates push together (AAAS Project 2061, n.d.).

25%

22%

PTM130

When two plates push into each other, both plates will stop moving (AAAS Project 2061, n.d.).

20%

17%

PTM131

When two plates push together, the edges of the plates break into small pieces (AAAS Project 2061, n.d.).

16%

15%

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.