Topic: Energy: Forms, Transformation, Transfer, and Conservation

Below is a list of key ideas related to Energy: Forms, Transformation, Transfer, and Conservation. 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.

Motion energy (kinetic energy) is associated with the speed and the mass of an object.

Students are expected to know that:

  1. The motion energy of an object depends on both the speed and the mass of the object and that motion energy depends only on these two factors. Motion energy does not depend on other factors such as size, shape, material the object is made of, or direction of motion.
  2. Any object that is moving has motion energy (kinetic energy) and the motion energy of an object that is not moving is zero.
  3. Objects that have the same mass and are traveling at the same speed have the same amount of motion energy.
  4. Increasing an object’s speed will increase the motion energy of the object (regardless of how much the speed is increased) and decreasing an object’s speed will decrease the motion energy of the object (assuming the mass of the object does not change).
  5. When the motion energy of an object increases, the speed of the object increases and when the motion energy of an object decreases, the speed of the object decreases (assuming the mass of the object does not change).
  6. For objects that have the same mass, the object with the greatest speed will have the greatest motion energy and the object with the lowest speed will have the least motion energy.
  7. For objects that have the same mass, the object with the greatest motion energy has the greatest speed and the object with the least motion energy has the least speed.
  8. For objects traveling at the same speed (greater than zero), the object with the greatest mass will have the greatest motion energy and the object with the least mass will have the least motion energy.
  9. For objects traveling at the same speed (greater than zero), the object with the greatest motion energy has the greatest mass and the object with the least motion energy has the least mass.
  10. For objects traveling with the same amount of motion energy, the object with the greatest mass will have the lowest speed and the object with the least mass will have the greatest speed.
  11. For objects traveling with the same amount of motion energy, the object with the greatest speed will have the least mass and the object with the lowest speed will have the greatest mass.

Boundaries:

  1. We feel that “motion energy” is a more descriptive label than “kinetic energy” for this form of energy. Assessment items will use the phrase “motion energy (kinetic energy)” to avoid confusing students who are familiar with the phrase “kinetic energy.”
  2. Students are not expected to know or use the formula ½mv2. The sub-ideas above describe qualitative relationships.
  3. Students are not expected to compare situations where both the mass and speed vary. In assessment items, either the mass or the speed will be held constant while the other varies so that both variables will not be changed at the same time. However, the case where one object is moving and the other is not (regardless of their masses) is valid.
  4. Assessment items will use miles per hour as the unit of speed.
  5. Note: The students are not expected to know the difference between “weight” and “mass.” All of the context used in the assessment items will be ones where “mass” and “weight” are proportional to each other. When two objects are being compared, they will be in the same location.
  6. This idea refers to motion with respect to the surface of the earth. An object is not moving if its position with respect to a point on the surface of the earth is not changing. Students are not expected to know that because every object is moving relative to some other object, no object has a unique claim to be at rest.
  7. This idea is limited to translational kinetic energy. Students are not expected to know about other forms of kinetic energy such as vibrational kinetic energy and rotational kinetic energy.
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

EG004004

A car has the most motion energy when it is traveling at the highest speed.

63%

66%

EG001005

For two balls that have the same mass, the ball that is rolling faster has more motion energy.

63%

65%

EG012002

A ball has more motion energy than a person when the ball is moving and the person is not moving.

61%

65%

EG001006

For two balls that have the same mass, the ball that is rolling faster has more motion energy.

62%

61%

EG003002

Two children that have the same mass and are sledding at the same speed have the same amount of motion energy.

56%

61%

EG007002

The motion energy of an object depends on the speed and mass of the object.

55%

60%

EG081001

Two objects that are moving at the same speed must have different masses in order to have different amounts of motion energy.

54%

60%

EG081002

Two objects that are moving at the same speed must have different masses in order to have different amounts of motion energy.

53%

61%

EG005003

Increasing the speed of an object increases its motion energy.

55%

57%

EG023002

Both a ball that is thrown and a ball that is dropped have motion energy while they are moving.

51%

55%

EG003003

Two children that have the same mass and are sledding at the same speed have the same amount of motion energy.

42%

51%

EG009003

For two objects that are traveling at the same speed, the object with more motion energy weighs more.

38%

49%

EG002002

For two pinecones falling at the same speed, the pinecone with more mass has more motion energy.

38%

44%

EG078001

When comparing two cars traveling at the same speed, the car that has more motion energy weighs more than the car that has less motion energy.

31%

42%

EG079001

When comparing two runners with different amounts of motion energy, the only way to know which one weighs more is to also know how fast each is running.

26%

34%

EG025001

In order to know which of two objects is moving faster, you need to know the weight (mass) of each object in addition to the motion energy.

19%

26%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

EGM017

A lighter object has more motion energy than a heavier object because lighter objects move faster than heavier objects (AAAS Project 2061, n.d.).

37%

29%

EGM016

Objects that are dropped do not have motion energy. For example, a dropped object doesn’t have motion energy because gravity is just pulling it down (Herrmann-Abell & DeBoer, 2010).

35%

33%

EGM011

The motion energy of an object does not depend on the mass of the object (Herrmann-Abell & DeBoer, 2009, 2010).

32%

31%

EGM055

The motion energy of an object depends on its size (AAAS Project 2061, n.d.).

20%

17%

EGM012

The motion energy of an object does not depend on speed (the motion energy of an object does not increase as the speed increases) (Kruger, 1990).

16%

16%

EGM057

The motion energy of an object depends on the material an object is made out of (AAAS Project 2061, n.d.).

18%

12%

EGM001

Energy is associated mainly with human beings, not inanimate objects (Finegold & Trumper, 1989; Kruger, 1990; Kruger, Palacino, & Summers, 1992; Leggett, 2003; Liu & Tang, 2004; Solomon, 1983; Stead, 1980; Trumper, 1990, 1993, 1997a, 1997b; Trumper & Gorsky, 1993; Watts, 1983).

14%

12%

EGM052

The motion energy of an object depends on the direction the object is traveling (AAAS Project 2061, n.d.).

13%

11%

EGM056

The motion energy of an object depends on its shape (AAAS Project 2061, n.d.).

11%

11%

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.

Thermal energy is associated with the temperature and the mass of an object and the material of which the object is made.

Students are expected to know that:

  1. The temperature, the mass of the object, and the material of which the object is made all affect the thermal energy of the object.
  2. Every object, regardless of whether it is a solid, a liquid, or a gas, has some thermal energy even if the object’s temperature is very low.
  3. Objects that are made of the same material, have the same mass and are at the same temperature have the same amount of thermal energy.
  4. The higher the temperature of an object, the more thermal energy the object has, and the lower the temperature of an object, the less thermal energy the object has.
  5. When the thermal energy of an object increases, the temperature of the object increases and when the thermal energy of the object decreases, the temperature of the object decreases (assuming the mass of the object does not change).
  6. For objects that are made of the same material and have the same mass, the object with the highest temperature will have the most thermal energy and the object with the lowest temperature will have the least thermal energy.
  7. For objects that are made of the same material and have the same mass, the object with the greatest thermal energy has the highest temperature and the object with the least thermal energy has the lowest temperature.
  8. For objects that are made of the same material and at the same temperature, the object with the greatest mass will have the most thermal energy and the object with the least mass will have the least thermal energy.
  9. For objects that are made of the same material and at the same temperature, the object with the greatest thermal energy has the greatest mass and the object with the least thermal energy has the least mass.
  10. Objects that are made of different materials may have different amounts of thermal energy even if they have the same mass and temperature.
  11. For objects that are made of the same material and have the same amount of thermal energy, the object with the greatest mass will have the lowest temperature and the object with the least mass will have the highest temperature.
  12. For objects that are made of the same material and have the same amount of thermal energy, the object with the highest temperature will have the least mass and the object with the lowest temperature will have the greatest mass.

Boundaries:

  1. Students are not expected to know or use the formulas associated with thermal energy, such as 3/2 kT and m(ΔT)Cp. The sub-ideas above describe qualitative relationships.
  2. This idea refers to macroscopic objects not individual atoms and molecules.
  3. Students are not expected to know the relationship between heat and temperature, that heat capacity is a measure of how much the temperature of an object will increase with the addition of a given amount of thermal energy, or why an object could feel colder than other objects at the same temperature. The idea that how an object feels does not necessarily reflect the temperature of the object is a prerequisite idea.
  4. Students are not expected to compare situations where both the mass and the temperature of the objects vary. In assessment items, either the mass or the temperature of the objects will be held constant while the other varies so that both variables will not be changed at the same time.
  5. Additionally, students are not expected to compare the thermal energy of objects that are made of different materials, e.g., we will ask students to compare the thermal energy of one apple to the thermal energy of another apple not apples to oranges.
  6. In this idea, the temperature changes will be limited to those that do not involve changes of state.
  7. Students are not expected to know that absolute zero is the temperature a substance would have if all atomic and molecular motion were to stop.
  8. Assessment items will use Fahrenheit as the units of temperature, for example, 80ºF.
  9. Students are not expected to know that temperature is not a characteristic property of substances.
  10. Note: The students are not expected to know the difference between “weight” and “mass.” The words “weight” or “weigh” are used as substitutes for “mass” in situations where such substitutions do not make any difference.
  11. Note: The term “heat” can be used in everyday conversation as a verb or a noun. When heat is used as a verb, the meaning is basically to raise the temperature of an object as in “I heated the water.” When heat is used as a noun, it usually is intended to mean some “energy.” While people often use the term “heat” as a synonym for thermal energy, that use is not scientifically correct. Technically, “heat” is the energy transferred from one system to another (or between a system and its environment) due to a temperature difference between the systems (or between the system and its environment). Thus the term “heat” should be used in a manner similar to the word “work” in that it should only be used to describe the energy transferred into or out of a system, not the energy in a system. Students are not expected to know the proper use of the term heat. To avoid confusion, the everyday use of the “heat” as a noun should be avoided in middle school instruction and beyond. The use of “heat” as a verb does not cause a problem, however.

Thermal energy of an object is associated with the disordered motions of its atoms or molecules and the number and types of atoms or molecules of which the object is made.

Students are expected to know that:

  1. The average speed of it atoms or molecules, the number of atoms or molecules, and the types of atoms or molecules of which the object is made all affect the thermal energy of the object.
  2. The thermal energy of an object is the sum of the motion energy (kinetic energy) of all of the individual atoms and molecules that make up the object.
  3. Since all matter is made up of atoms and molecules that are in constant random motion, all matter has some thermal energy.
  4. When the average speed of the atoms and molecules of an object increases, the motion energy of the atoms and molecules increases and, therefore, the thermal energy of the object increases. When the average speed of the atoms and molecules of an object decreases, the motion energy of the atoms and molecules decreases and, therefore, the thermal energy of the object decreases.
  5. When the thermal energy of an object increases, the motion energy and average speed of the atoms and molecules of the object increases. When the thermal energy of an object decreases, the motion energy and average speed of the atoms and molecules of the object decreases.
  6. For objects that are made of the same number and type of molecules, the object that is made up of the atoms and molecules with the highest average speed will have the most thermal energy and the object that is made up of the atoms and molecules with the lowest average speed will have the least thermal energy.
  7. For objects that are made of the same number and type of atoms and molecules, the object with the greatest thermal energy is made up of the atoms and molecules with the highest average speed and the object with the least thermal energy is made up of the atoms and molecules with the lowest average speed.
  8. With all else equal, the greater the number of atoms and molecules, the greater the thermal energy and the fewer the number of atoms and molecules, the lower the thermal energy.
  9. With all else equal, the greater the thermal energy, the greater the number of atoms and molecules and the lower the thermal energy, the fewer the number of atoms and molecules.

Boundaries:

  1. Students are not expected to know or use the formulas associated with thermal energy, such as 3/2 kT and m(ΔT)Cp. They are also not expected to calculate the thermal energy by summing the kinetic energy of the individual molecules. The sub-ideas above describe qualitative relationships.
  2. Students are not expected to know which kinds of atoms/molecules have more thermal energy.
  3. They are also not expected to know about internal energy and the potential energy that exists between the atoms and molecules of a substance.
  4. Students are not expected to know that absolute zero is the temperature a substance would have if all atomic and molecular motion were to stop.
  5. Students are not expected to know the term “kinetic energy.” Assessment items will use the phrase “motion energy (kinetic energy)” to avoid confusing students who are familiar with the phrase “kinetic energy.”
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

EGM031

Thermal energy is not related to the number of molecules that make up an object (Herrmann-Abell & DeBoer, 2009).

39%

37%

EGM028

Thermal energy is not related to the type of molecule that makes up an object (Herrmann-Abell & DeBoer, 2009).

37%

35%

EGM062

Thermal energy is not related to the kinetic energy of the molecules that make up an object (AAAS Project 2061, n.d.).

27%

25%

EGM021

Cold/frozen objects do not have any thermal energy (AAAS Project 2061, n.d.).

19%

18%

EGM050

Thermal energy is not related to the speed of the molecules that make up an object (AAAS Project 2061, n.d.).

20%

18%

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.

Gravitational potential energy is associated with the distance an object is above a reference point, such as the center of the earth, and the mass of the object.

Students are expected to know that:

  1. The gravitational potential energy of an object depends on both the distance an object is above the center of the earth and the mass of the object and that gravitational potential energy depends only on these two factors. Gravitational potential energy does not depend on other factors such as speed, size, shape, material the object is made of, or the path the object took to get to the distance above the center of the earth.
  2. Objects that have the same mass and are equal distances from the center of the earth have the same amount of gravitational potential energy.
  3. Increasing the distance an object is from the center of the earth will increase the gravitational potential energy of the object (assuming the mass of the object does not change) and decreasing the distance an object is from the center of the earth will decrease the gravitational potential energy of the object (assuming the mass of the object does not change).
  4. If the gravitational potential energy of an object increases, the distance the object is from the center of the earth must have increased (assuming the mass of the object does not change) and if the gravitational potential energy of an object decreases, the distance the object is from the center of the earth must have decreased (assuming the mass of the object does not change).
  5. For objects that have the same mass, the object farthest from the center of the earth will have the most gravitational potential energy and the object closest to the center of the earth will have the least gravitational potential energy.
  6. For objects that have the same mass, the object with the greatest gravitational potential energy is the farthest from the center of the earth, and the object with the least gravitational potential energy is the closest to the center of the earth.
  7. For objects that are equal distances from the center of the earth (greater than zero), the object with the greatest mass will have the most gravitational potential energy and the object with the least mass will have the least gravitational potential energy.
  8. For objects that are equal distances from the center of the earth (greater than zero), the object with the greatest gravitational potential energy has the greatest mass and the object with the least gravitational potential energy has the least mass.
  9. For objects that have the same amount of gravitational potential energy, the object with the greatest mass is closest to the center of the earth and the object with the least mass is the farthest from the center of the earth.
  10. For objects that have the same amount of gravitational potential energy, the object that is the farthest from the center of the earth will have the least mass and the object that is the closest to the center of the earth will have the greatest mass.

Boundaries:

  1. Students are not expected to know the meaning of the term “potential.”
  2. Students are not expected to know or use formulas associated with gravitational potential energy, such as mass x gravitational constant x height/distance (mgh). The sub-ideas above describe qualitative relationships.
  3. As a result, students are not expected to compare situations where both the mass and distance vary. In assessment items, either the mass or the distance will be held constant while the other varies so that both variables will not be changed at the same time.
  4. Additionally, the distance used in the assessment items will be the distance above the center of the earth unless a substitute reference plane, such as the floor, is explicitly stated in the assessment item. When this is the case, the reference plane will be the lowest plane in the context so that there will be only positive values for the distance.
  5. Note: The students are not expected to know the difference between “weight” and “mass.” All of the context used in the assessment items will be ones where “mass” and “weight” are proportional to each other. The earth will be used as the context for all assessment items.
  6. Note: Any plane on which all points are essentially equidistant from the center of the earth, such as the floor of a room, can be used as a substitute for the center of the earth in determining the amount of gravitational potential energy an object has. Because all points on this reference plane are considered to be equidistant from the center of the earth, all objects on the plane can be considered to have zero gravitational potential energy. (There will be only one reference plane that applies to all objects in the situation.) In assessment items the “reference plane” will be referred to as a “reference point.”
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

EG071002

Two pictures that weigh the same and are hung the same height above the floor have the same amount of gravitational potential energy.

54%

59%

EG088001

When two children who weigh the same are on a teeter-totter, the child who is up has more gravitational potential energy than the child who is down.

53%

57%

EG015003

The mass of a rock will affect the gravitational potential energy of a rock on top of a cliff.

47%

55%

EG016003

The gravitational potential energy of an object depends on the mass of the object and the object's distance from the center of the earth.

46%

56%

EG018004

For two books on a table, the book that weighs more has more gravitational potential energy.

47%

49%

EG020003

For two objects that are the same distance from the center of the earth, the object with more gravitational potential energy weighs more.

45%

51%

EG013004

When a coconut falls from a tree, it has the most gravitational potential energy at its highest point above the ground.

41%

50%

EG022003

A person will have the same amount of gravitational potential energy at the top of a mountain regardless of the path the person takes to get there.

37%

51%

EG090001

Two identical balls that are thrown up in the air will have the same amount of gravitational potential energy when they are at the same height above the ground.

35%

42%

EG093001

The gravitational potential energy of an object depends on the object’s distance from the center of the earth but not the speed of the object.

31%

39%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

EGM040

The gravitational potential energy of an object depends upon the path the object takes to get to the distance above the reference point (Singh & Rosengrant, 2001, 2003; Herrmann-Abell & DeBoer, 2010).

63%

49%

EGM042

The gravitational potential energy of an object depends on the speed of the object (the gravitational potential energy increases as the object's speed increases) (Herrmann-Abell & DeBoer, 2010).

38%

35%

EGM060

For two identical objects thrown up into the air, they must have been thrown with the same amount of force to have the same amount of gravitational potential energy (AAAS Project 2061, n.d.).

28%

27%

EGM038

The gravitational potential energy of an object does not depend on the mass of the object (AAAS Project 2061, n.d.).

25%

24%

EGM061

The gravitational potential energy of an object does not depend on the distance the object is above the ground (AAAS Project 2061, n.d.).

24%

21%

EGM053

The gravitational potential energy of an object decreases as an object moves farther away from the center of the earth and the gravitational potential energy increases as the object falls toward the earth (AAAS Project 2061, n.d.).

22%

19%

EGM039

An object has gravitational potential energy only at the edge of a cliff or table but not at some distance from the edge (Kruger, 1990).

18%

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.

Elastic potential energy is associated with the stretching or compressing of an elastic object and how difficult it is to stretch or compress the object.

Students are expected to know that:

  1. An elastic object is an object that changes shape when stretched or compressed and returns to its original shape on when not stretched or compressed.
  2. An elastic object that is not stretched or compressed has no elastic energy.
  3. Elastic objects that are made of the same material and are stretched (or compressed) the same amount have the same amount of elastic energy.
  4. The elastic energy of an elastic object can be increased by stretching or compressing the object out of its original shape. Increasing the amount the object is stretched or the amount of the object is compressed, increases the elastic energy of the object and decreasing the amount the object is stretched or compressed, decreases the elastic energy of an object.
  5. For elastic objects that are identical except for how much they are stretched or compressed, the object stretched or compressed the most will have the most elastic energy and the object stretched or compressed the least will have the least elastic energy.
  6. For elastic objects that are identical except for how much they are stretched or compressed, the object with the most elastic energy is stretched or compressed the most and the object that has the least elastic energy is stretched or compressed the least.
  7. For elastic objects stretched or compressed the same amount (greater than zero), the object that is the most difficult to stretch or compress will have the most elastic energy and the object that is the least difficult to stretch or compress will have the least elastic energy.
  8. For elastic objects stretched or compressed the same amount (greater than zero), the object that has the most elastic energy is the most difficult to stretch or compress and the object that has the least elastic energy is the least difficult to stretch or compress.
  9. There is a limit to how much an object can be stretched or compressed. If an elastic object is stretched or compressed too much, it may break or not be able to return to its original shape.
  10. How much an object is stretched or compressed is measured relative to its unstretched or uncompressed state. They should know that the unstretched or uncompressed length of an elastic object does not determine the amount of elastic energy.

Boundaries:

  1. Students are not expected to know the meaning of the term “potential.”
  2. Students are not expected to know or use formulas associated with elastic energy, such as ½kx2. The sub-ideas above describe qualitative relationships.
  3. As a result, students are not expected to compare situations where both the amount of stretching or compressing and the properties of the object vary. In assessment items, either the amount of stretching or compressing or the properties of the object will be held constant while the other varies so that both variables will not be changed at the same time.
  4. Students are not expected to know which objects are elastic. Assessment items will use only familiar elastic objects such as springs, rubber bands, and rubber balls. Students are not expected to know the stiffness/rigidity of specific materials or the spring constants of specific springs. In assessment items, the relative rigidity will be provided when necessary.
  5. When comparing objects in assessment items, we will not have a situation where one object is stretched and another object is compressed. Additionally, we would not compare an object in a stretched and compressed state.
  6. In assessment items, objects will not be stretched or compressed beyond the point where they would return to their original shape (i.e. no plastic deformation).
  7. When dealing with springs, students are not expected to know the effect of combining springs in series or parallel on the elastic energy of the springs. Students are also not expected to know about how the geometry of the spring relates to the overall elasticity of the spring.

Energy can be transformed (converted) within a system.

Students are expected to know that:

  1. Within a system, one form of energy can be transformed into one or more other forms of energy.
  2. A decrease in one form of energy within a system is associated with an increase in one or more other forms of energy (unless energy is transferred into or out of the system). Similarly, an increase in one form of energy within a system is associated with a decrease in one or more other forms of energy (unless energy is transferred into or out of the system).
  3. Any form of energy can be transformed to other forms of energy and any form of energy can result from a transformation.
  4. Energy and force are two different concepts and one cannot be transformed into the other.
  5. Energy transformations can occur when energy is transferred from one system to another.
  6. Most of what goes on in the universe—from exploding stars and biological growth to the operation of machines and the motion of people—involves some form of energy being transformed into one or more other forms of energy.

Boundaries:

  1. Although students are expected to know that when energy is transformed, a decrease of one form of energy is accompanied by an increase in one or more other forms of energy and vice versa, they are not expected to know that the total amount of energy in the system is conserved.
  2. Students are not expected to keep track of how much of one form is converted into another.
  3. Students are also not expected to know the relationship between energy and work.
  4. They will be assessed on energy transformations involving motion energy (kinetic energy), thermal energy, gravitational potential energy, and/or elastic potential energy.
  5. Students will not be assessed on energy transformations involving electrical energy, sound energy, chemical potential energy, or radiant energy because we have not yet developed clarifications and items aligned to these ideas.
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

NG016003

When a ball rolls downhill, the gravitational potential energy of the ball is transformed into motion energy.

53%

58%

NG009005

Both gravitational potential energy and motion energy are involved in an energy transformation when a book falls. As the book is falling, its gravitational potential energy decreases and its motion energy increases.

50%

57%

NG003003

Gravitational potential energy is transformed into motion energy and thermal energy when coasting down a hill on a bicycle.

45%

56%

NG004003

Gravitational potential energy is transformed into motion energy as a rock falls from a cliff.

43%

55%

NG018003

The thermal energy of a ball and a track increases the entire time the ball is rolling along the track because both the gravitational potential energy and the motion energy of the ball are converted into thermal energy.

45%

51%

NG005003

As a piece of clay falls, its gravitational potential energy is converted to motion energy, and as it hits the floor its motion energy is converted into thermal energy.

47%

49%

NG015003

As a ball rolls down a ramp, the gravitational potential energy of the ball decreases and the motion energy of the ball increases because gravitational potential energy is transformed into motion energy.

42%

54%

NG099001

When skateboarding down a hill, gravitational potential energy is transformed into motion energy and thermal energy.

42%

53%

NG100001

When a ball is falling down, the gravitational potential energy of the ball is transformed into motion energy but the elastic energy of the ball is not.

42%

50%

NG001003

Water dripping from a faucet into a sink is an example of the transformation of gravitational potential energy into motion energy.

42%

48%

NG017003

The motion energy of a ball rolling back and forth in a curved track is converted to gravitational potential energy only when it is rolling uphill.

31%

38%

NG013002

As a rubber balls falls to the floor, the motion energy of the ball increases and the gravitational potential energy of the ball decreases because the gravitational potential energy is transformed into motion energy.

27%

39%

NG079002

The motion energy of a book sliding across a table is transformed into thermal energy, not into a force.

26%

33%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

NGM005

Energy can be transformed into a force (AAAS Project 2061, n.d.).

63%

58%

NGM010

Energy can be created (Kruger, 1990; Lovrude, 2004; Papadouris et al., 2008).

28%

20%

EGM044

Gravitational potential energy is the potential to fall; an object will lose all of its gravitational potential energy as soon as it starts to fall (Herrmann-Abell & DeBoer, 2010; Loverude, 2004).

18%

16%

NGM011

Gravitational potential energy cannot be converted into thermal energy (AAAS Project 2061, n.d.).

17%

14%

NGM009

An object has energy within it that is used up as the object moves (Brook & Driver, 1984; Kesidou & Duit, 1993; Loverude, 2004; Stead, 1980).

16%

14%

NGM003

Motion energy is not transformed into thermal energy, especially when there is no noticeable temperature increase (Brook & Wells, 1988; Kesidou & Duit, 1993).

16%

14%

NGM002

One form of energy cannot be transformed into another form of energy (e.g. chemical energy cannot be converted to kinetic energy) (Brook & Driver, 1984).

11%

8%

NGM006

Motion energy cannot be transformed into gravitational potential energy (AAAS Project 2061, n.d.).

11%

9%

NGM007

Gravitational potential energy cannot be transformed into motion energy (AAAS Project 2061, n.d.).

10%

8%

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.

Energy can be transferred from one system to another (or from a system to its environment) in different ways: by conduction, mechanically, electrically, or by radiation (electromagnetic waves).

Students are expected to know that:

  1. Thermal energy can be transferred by conduction when a warmer object (including liquids, like water, and gases, like air) is in contact with a cooler one. [Note: this is not the only way thermal energy can be transferred. See boundary statement 3.]
    1. Two objects must be in contact with each other for thermal energy to be transferred by conduction (which is not the case for radiation). This means that the sun does not transfer thermal energy directly to the earth.
    2. There must be a temperature difference between the objects in contact for thermal energy to be transferred by conduction. The greater the temperature difference the greater the amount of thermal energy that can be transferred by conduction (assuming the mass or type of material is held constant).
    3. The thermal energy transferred by conduction goes from the warmer object to the cooler one.
    4. As thermal energy is transferred by conduction the thermal energy (and temperature) of the cooler object will increase and the thermal energy (and temperature) of the warmer object will decrease until the objects are at the same temperature. [This sub-idea assumes that neither object changes state, in which case the temperature of the object would not increase or decrease as the change of state was occurring. Assessment items are limited to contexts in which there is no change of state.]
  2. Energy can be transferred mechanically when one object pushes or pulls on another object over a distance.
    1. In order for energy to be transferred mechanically there must be a change in position and/or shape (the push or pull must act over a distance).  This energy transfer will stop if the motion/changing of position stops. 
    2. Energy will be transferred mechanically the entire time the push or pull is acting (in the direction of motion) and energy transfer will stop when the push or pull stops.
    3. When two pushes or pulls act over the same distance, the stronger push or pull transfers more energy mechanically than the weaker push or pull.
  3. Energy can be transferred electrically when an electrical source, such as a battery or generator, is connected in a complete circuit to an electrical device, such as a light bulb, speaker, heater, or motor.
  4. Energy can be transferred by electromagnetic radiation.
    1. Electromagnetic radiation is always given off by all objects and energy is transferred when this electromagnetic radiation is absorbed by another object.
    2. Electromagnetic radiation can transfer energy through space; therefore, objects do not need to be in contact with each other in order to transfer energy by radiation.
    3. The amount of electromagnetic radiation given off by an object can depend on the temperature of the object. The higher the temperature of an object, the more electromagnetic radiation the object gives off.
    4. When energy is transferred to an object by radiation, the temperature and thermal energy of the object typically increase.  When energy is transferred from an object by radiation, the temperature and thermal energy of the object typically decrease. [This sub-idea assumes that neither object changes state, in which case the temperature of the object would not increase or decrease. Assessment items are limited to contexts in which there is no change of state.]
    5. This is the mechanism by which the sun transfers energy to the earth.
  5. Students should know that as energy is transferred from one system to another, energy transformations can also occur.

Boundaries:

  1. Examples of mechanical energy transfer that students should be familiar with include the energy transfer that occurs when billiard balls hit each other, when a ball is thrown or kicked, when a baseball or golf ball is hit with a bat or club, when an object is set in motion by a rubber band or spring, or when a bobsled or swing is pushed. Assessment items should use contexts in which it is clear that the object supplying the energy has less energy after the transfer and the object receiving the energy has more energy after the transfer. For example, when a ball is thrown, it may be hard to appreciate that your body is loosing energy. Note that this may also be true for other forms of transfer. For example, it may not be obvious that an object that radiates energy loses energy.
  2. Students are not expected to know that conduction occurs through collisions of atoms.
  3. Students are not expected to know that convection and diffusion are other ways by which thermal energy is transferred.
  4. Although students are expected to know that when energy is transferred, a decrease of energy somewhere is accompanied by an increase in energy somewhere else and vice versa, they are not expected to know that the total amount of energy in the system is conserved.
  5. Students are not expected to keep track of how much energy is transferred by each mechanism.
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

NG034003

The thermal energy of a toy bear in the sunlight will be greater than the thermal energy of an identical bear in the shade because more energy is transferred directly from the sun to the bear in the sunlight than to the bear in the shade.

70%

74%

NG059002

Energy is transferred when a battery is used to power a cell phone, and energy is transferred when the sun shines on a plant.

65%

69%

NG055002

Energy is transferred when a battery is connected to a light bulb in a complete circuit, and energy is transferred when wind causes a windmill to rotate.

60%

62%

NG060002

Energy is transferred when a waterfall is used to turn a wheel, and energy is transferred when a fire in a fireplace is used to heat a room.

58%

64%

NG025003

While a student holds a cold piece of metal in her hand, the metal will get warmer because thermal energy is transferred from the student's hand to the metal.

53%

66%

NG062002

A hot cookie will transfer more thermal energy to a cold plate than a cookie that is at room temperature because the temperature difference between the hot cookie and the cold plate is greater than the temperature difference between the cookie at room temperature and the cold plate.

53%

65%

NG056004

Energy is transferred when a cold spoon is placed in a cup of hot tea, and energy is transferred when an ice cube is placed in a cup of hot tea.

55%

58%

NG056003

Energy is transferred when a cold spoon is placed in a cup of hot tea, and energy is transferred when a spring is used to roll a ball across the floor.

51%

63%

NG047003

When a ball that is 50ºF is placed in a bucket of water that is 80ºF, thermal energy is transferred from the water to the ball until they are both the same temperature.

47%

59%

NG064002

Energy is transferred from the sun to a tree as light that is radiated from the sun is absorbed by the tree.

48%

51%

NG032003

A girl feels warmer when she is in the sun than when she is in the shade under a tree because energy is being transferred directly from the sun to the girl.

48%

50%

NG056002

Energy is transferred when an ice cube is placed in a cup of hot tea, and energy is transferred when a spring is used to roll a ball across the floor.

41%

61%

NG054002

Energy is transferred electrically from a power plant to a light bulb in a lamp only when the lamp is turned on because energy can be transferred electrically only when there is a complete circuit.

48%

48%

NG033003

A girl feels warmer when she is in the sunlight than when she is in the shade under an umbrella because energy is being transferred directly from the sun to the girl when she is in the sunlight.

45%

49%

NG057002

Energy is transferred when a person touches a cold piece of metal, and energy is transferred when a lamp shines light on a table.

43%

51%

NG061002

When cold butter is placed on top of hot corn, thermal energy is transferred from the corn to the butter but not from the butter to the corn.

43%

47%

NG049003

When a spring is used to shoot a cart across the floor, the spring transfers energy to the cart. (This item uses bar graphs to illustrate the amount of elastic energy the spring has and the amount of motion energy the cart has as the cart is rolling across the floor.)

39%

50%

NG047004

When a ball that is 80ºF is placed in a bucket of water that is 50ºF, thermal energy is transferred from the ball to the water until they are both at the same temperature.

39%

49%

NG035002

The heating coils on an electric stove give off energy in the form of electromagnetic radiation at all temperatures, not just when they are hot.

40%

47%

NG031003

If a hot frying pan is placed on the counter, after a while the frying pan, the counter, and the air will be at the same temperature because thermal energy will be transferred from the frying pan to the counter and from the frying pan to the air.

39%

44%

NG027002

When a cold object is in contact with a warm object, thermal energy is transferred from the warm object to the cold object.

35%

43%

NG101001

When a warm can of soda is in contact with cold water, thermal energy is transferred from the can of soda to the water so the can of soda gets cooler and the water gets warmer.

33%

46%

NG058002

Energy is transferred when a person comes in contact with cold air, and energy is transferred when an electric generator is used to run a motor.

35%

41%

NG023002

When cold water is poured into a cup that is at room temperature, thermal energy is transferred from the cup to the water until they are both at the same temperature.

31%

42%

NG022003

When water that is 40ºF is poured into a cup that is 70ºF, thermal energy is transferred from the cup to the water until they reach the same temperature.

31%

41%

NG045002

Both a light bulb and an ice cream cone radiate energy because all objects radiate energy.

23%

30%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

NGM010

Energy can be created (Kruger, 1990; Lovrude, 2004; Papadouris et al., 2008).

50%

40%

EGM035

Springs or other elastic objects have the same amount of elastic energy regardless of how much they are stretched or compressed (AAAS Project 2061, n.d.).

38%

33%

NGM016

When two objects at different temperatures are in contact with each other, thermal energy is transferred from the warmer object to the cooler object and “coldness” or ”cold energy” is transferred from the cooler object to the warmer object (AAAS Project 2061, n.d.).

37%

35%

NGM057

Energy is not transferred from one object to another unless those objects are in direct contact with each other (AAAS Project 2061, n.d.).

35%

31%

NGM031

Only objects that are glowing can transfer energy in the form of electromagnetic radiation (AAAS Project 2061, n.d.).

31%

28%

NGM056

Electrical sources such as batteries transfer energy all the time, even when there is not a complete circuit (AAAS Project 2061, n.d.).

26%

27%

NGM032

Only hot objects can transfer energy in the form of electromagnetic radiation (AAAS Project 2061, n.d.).

25%

21%

NGM013

Thermal energy will continue to be transferred by conduction even after objects in contact with each other reach the same temperature; the temperature of the object getting warmer will continue to increase and the temperature of the object getting cooler will continue to decrease (Kesidou & Duit, 1993).

23%

21%

NGM015

When a cold and a warm object are placed in contact with each other, the warm object gets colder and the cold object gets warmer because “coldness” is transferred from one object to the other (Brook, Briggs, Bell, & Driver, 1984; Newell & Ross, 1996).

23%

18%

NGM054

Only hot or warm objects transfer thermal energy (AAAS Project 2061, n.d.).

23%

16%

NGM036

Only the sun transfers energy in the form of electromagnetic radiation (AAAS Project 2061, n.d.).

11%

11%

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.

Regardless of what happens within a system, the total amount of energy in the system remains the same unless energy is added to or released from the system.

Students should know that:

  1. Regardless of what happens within a system, the total amount of energy in the system remains the same unless energy is added to or released from the system, even though the forms of energy present may change.
  2. If the total amount of energy in a system seems to decrease or increase, energy must have gone somewhere or come from somewhere outside the system.
  3. If no energy enters or leaves a system, a decrease of one form of energy by a certain amount within the system must be balanced by an increase of another form of energy by that same amount within the system (or a net increase of multiple forms of energy by that same amount). Similarly, an increase of one form of energy by a certain amount within a system must be balanced by a decrease of another form of energy by that same amount within the system (or a net decrease of multiple forms of energy by that same amount).
  4. Energy can neither be created nor destroyed but it can be transferred and/or transformed.
  5. If energy is transferred to or from a very large system (or a very complex system), increases or decreases of energy may be difficult to detect and, therefore, it may appear that energy was not conserved.

Boundaries:

  1. Students are not expected to quantitatively keep track of changes of energy in a system.
  2. Assessment items will avoid using the phrase “energy conservation” or “conservation of energy” because of the misconceptions associated with them (see list of misconceptions).
  3. Students are not expected to know about energy-mass conversions such as nuclear reactions or other subatomic interactions.
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

NG083003

Energy is transferred to the air around hot food as the food cools even though the temperature of the air does not appear to increase.

53%

59%

NG071002

Assuming that no energy is transferred between a ball and the curved track it is moving in, or between the ball and the air around it, the ball will move down the track and then up to a point equal to the height from which it started.

51%

55%

NG084002

Assuming that no energy is transferred between a ball and the curved track it is moving in, or between the ball and the air around it, the ball will only move to a height equal to the height from which it started. It will not be able to go over a hill that is higher than the point from which it started.

46%

52%

NG085002

Assuming that no energy is transferred between a ball and the curved track it is moving in, or between the ball and the air around it, the ball will not have enough energy to go over a hill that is higher than the height from which it started because the total energy of the system has to remain the same.

39%

51%

NG075003

Assuming that no energy is transferred between a ball and the curved track it is moving in, or between the ball and the air around it, a ball on a curved track will reach a point as high as the point from which it started because as the ball moves down the track, its gravitational potential energy will change into motion energy, and as the ball goes up the other side, its motion energy will be changed back into an equal amount of gravitational potential energy.

36%

44%

NG070002

Assuming that no energy is transferred between a ball and the curved track it is moving in, or between the ball and the air around it, the ball will move to a height equal to the height from which it started.

32%

44%

NG088003

When a student shoots a rubber band across the room, the elastic energy of the rubber band is transformed into motion energy, and the total amount of energy stays the same. (This item uses bar graphs to depict the amount of each kind of energy.)

32%

44%

NG089003

The total amount of energy in a lunch box containing only an ice pack and the air around it remains the same even after the ice pack gets warmer and the air gets colder. (This item uses bar graphs to depict the amounts of each form of energy.)

30%

38%

NG081003

The total energy inside a closed cooler filled with ice and a can of soda stays the same even though the can of soda gets colder, because the amount of energy that the can of soda lost is equal to the amount of energy that the ice gained.

27%

42%

NG080003

As a clay ball falls and hits the ground, the total amount of energy in the system stays the same because the decrease in energy due to the clay ball moving closer to the ground is equal to the increase in energy due to the clay ball and the floor getting warmer.

26%

38%

NG096002

The total amount of energy a ball has does not change after it goes down and up a dip because the total energy of the system (ball and track) does not change (assuming no energy transfer between the ball and the track and the ball and the air around it).

24%

38%

NG078002

After a rubber band is used to shoot a toy car across the floor, the total energy of the system will remain the same because the increase in the motion energy (kinetic energy) of the car is the same as the decrease in the elastic energy of the rubber band.

23%

33%

NG095002

The total amount of energy a ball has does not change after it goes down and up a dip because the total energy of the system (ball and track) does not change (assuming no energy transfer between the ball and the track and the ball and the air around it).

22%

34%

NG065004

A pendulum stops swinging because the motion energy of the ball is transferred somewhere else, like the air, as the ball swings from side to side.

20%

32%

NG094002

Assuming no energy transfer between a ball and the track it is moving in, the amount of energy the ball has after it goes over a hill will be the same as before it went over the hill because the total amount of energy in the system did not change.

18%

31%

NG092002

Assuming no energy transfer between a ball and the track it is moving in, the amount of energy the ball has after it goes over a hill will be the same as before it went over the hill.

18%

27%

NG086002

Assuming no energy transfer between a roller coaster car and the track it is moving in or between the car and the air around it, all of the hills that a roller coaster car can get over must be lower than the height of the starting point.

19%

25%

NG090002

Assuming no energy transfer between a ball and the track it is moving in, the speed of the ball will be the same before and after rolling over a hill because the total amount of energy in the system does not change.

12%

18%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

NGM043

For a ball traveling over a frictionless hill, the steepness of the path is the most important factor affecting the ball’s speed and motion energy (Duit, 1981).

37%

33%

EGM035

Springs or other elastic objects have the same amount of elastic energy regardless of how much they are stretched or compressed (AAAS Project 2061, n.d.).

39%

30%

NGM010

Energy can be created (Kruger, 1990; Lovrude, 2004; Papadouris et al., 2008).

33%

28%

NGM009

An object has energy within it that is used up as the object moves (Brook & Driver, 1984; Kesidou & Duit, 1993; Loverude, 2004; Stead, 1980).

31%

29%

NGM044

For a ball traveling over a frictionless hill, the length of the path is the most important factor affecting the ball’s speed and motion energy (Duit, 1981).

26%

21%

NGM060

Energy can be destroyed (Kruger, 1990; Trumper, 1998).

22%

19%

NGM037

An object always gains energy as it moves. For example, the height that a pendulum reaches after it is released is greater than its starting height because it gains energy as it swings (Loverude, 2004).

19%

18%

EGM048

Living things give inanimate objects energy by carrying or pushing them. For example, a person gives a bike energy by riding it or a bird give a stick energy by carrying it (Herrmann-Abell & DeBoer, 2010).

17%

13%

NGM045

Hills are speed booster, which means that the speed of a ball after rolling over a hill is greater than the speed of the ball before reaching the hill (Duit, 1981).

13%

10%

NGM059

Energy cannot be transferred from one object to another (AAAS Project 2061, n.d.).

12%

11%

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.