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

Key Idea: A decrease in energy in one object or set of objects always is accompanied by an increase in energy in another object or set of objects.

Sub-Ideas
Items & Student Performance
Misconceptions
NGSS

Students should know that:

The amount of energy in an object or set of interacting objects (system) can change. When energy is transferred to a system, the amount of energy in that system increases (assuming no energy is transferred out of the system). When energy is transferred out of a system, the amount of energy in that system decreases (assuming no energy is transferred to the system).
Whenever there is an increase in the amount of energy in one object or set of objects, there will be a decrease in the amount of energy in another object or set of objects.

Boundaries:

Assessment items do not assess the idea that the increase in energy somewhere equals the decrease in energy somewhere else. This idea is covered at the advanced level. Assessment items may use the misconceptions that energy can be created or destroyed as distractors but the idea that because energy cannot be created destroyed any increase in energy must be equally balanced by a decrease in energy somewhere else will not be assessed.
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 4–5	Grades 6–8	Grades 9–12	Select This Item for My Item Bank
RG152002	As a boy pushes a girl on a swing, the boy’s energy decreases, and the girl’s energy increases because the boy transferred some of his energy to the girl when he pushed her.	47%	57%	62%
RG124002	A child places a small stone in a slingshot and pulls the elastic band back. When the elastic band is released, the energy of the stone increases, and the energy of the elastic band decreases.	45%	47%	49%

Frequency of selecting a misconception
Misconception ID Number	Student Misconception	Grades 4–5	Grades 6–8	Grades 9–12
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).	23%	18%	15%
RGM075	The amount of elastic potential energy an object has is not related to how much it is stretched or compressed.	15%	14%	13%
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).	15%	12%	12%

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.

NGSS Statements
Code	Statement
PS3.A MS	Motion energy is properly called kinetic energy; it is proportional to the mass of the moving object and grows with the square of its speed.
PS3.A MS	A system of objects may also contain stored (potential) energy, depending on their relative positions.
PS3.B MS	When the motion energy of an object changes, there is inevitably some other change in energy at the same time.