Science Assessment ~ Items ~ AP013005

A teacher shows his class a toy called a Newton’s cradle. The toy is made up of a series of identical steel balls suspended on a frame as shown in the picture below.

The teacher pulls the ball on the left side toward the left and then releases it. Watch the video below to see what happens.

The students notice that the balls slow down and eventually stop swinging. The teacher asks the students to watch the video again and look for evidence that would help them explain why the balls stopped swinging.

1. Watch the video again and pay close attention to the heights of the balls as they swing. How do the heights of the balls change from the moment the teacher let go of the first ball to the end of the video?

2. Watch the video again and pay close attention to the sound produced during the video. What causes the sound to be produced?

3. How did the amount of energy that the balls have change from the moment the teacher let go of the first ball to the end of the video?

4. Write an argument for why the balls stop swinging. Your argument should begin with a claim. Then support your claim with evidence. Your evidence should be based on observations about the height of the balls and sound that you hear. Your argument should end with reasoning that links the evidence to your claim using ideas about energy transfer.

Claim:

Evidence:

Reasoning:

Details
Performance
NGSS

Topic: 3D Energy Tasks
Scoring Rubric: Q1; Student describes the correct observation

The height the ball swings to decreases over time; Q2; Student describes the cause of an effect

The sound is caused by collisions between the balls.; Q3; Student describes energy changes

The amount of energy the balls have decreases over time.; Q4; 1. Student makes a claim

The balls stop swinging because energy is transferred away from the balls/cradle.

Note: Saying that the energy is lost is ok as long as the student does not mention the energy being destroyed.

2. Student lists evidence

The balls reach a lower height each time they swing.

A sound is heard as the balls hit each other.

3. Student either states or uses a general science idea

Moving slower means less kinetic energy (i.e., the slower moving ball has less kinetic energy). [links speed and energy]

A lower height means less gravitational potential energy (i.e., the ball that reaches lower height has less gravitational potential energy). [links height and energy]

When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object (i.e., as the balls swing, they interact with the air [air resistance or friction], causing energy to transfer from the balls to the air). [links forces and energy transfer]

Note: The use of the word "force" is not required here.

Sound is an indicator of energy transferred to the surroundings (i.e., the sound the balls make when they hit transfers energy to the surroundings). [links sound and energy transfer]

4. Student uses reasoning to link evidence and science ideas to the claim

The balls stop swinging because energy was transferred away from the cradle by the sound made when the balls collide resulting in less and less energy to swing.

OR

The balls stop swinging because energy was transferred from the balls to the air as the ball interacts with the air (because of air resistance/forces) resulting in less and less energy to swing.

Percent of Points Earned

Chart showing distrubtion of responses for Item AP013005

Points Earned

	Avg. Earned	Possible	Percent
Q1	0.46	1	46%
Q2	0.72	1	72%
Q3	0.51	1	51%
Q4	0.94	4	24%

Overall Task Difficulty

	Total Points Earned	Total Points Possible	Total Percent
	2.63	7	38%

n = 237

Note: The total percent is a weighted average based on the total number of points earned divided by the total number of points possible.

Science and Engineering Practices: SEP3 Make observations and/or measurements to produce data to serve as the basis for evidence for an explanation of a phenomenon or test a design solution.
SEP6 Apply scientific ideas, principles, and/or evidence to construct, revise and/or use an explanation for realworld phenomena, examples, or events.
Crosscutting Concepts: CC2 Cause and effect relationships are routinely identified, tested, and used to explain change.
CC5 The transfer of energy can be tracked as energy flows through a designed or natural system.
Disciplinary Core Ideas: PS3.A 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 A system of objects may also contain stored (potential) energy, depending on their relative positions.
PS3.B Energy is present whenever there are moving objects, sound, light, or heat. When objects collide, energy can be transferred from one object to another, thereby changing their motion. In such collisions, some energy is typically also transferred to the surrounding air; as a result, the air gets heated and sound is produced.
PS3.B When the motion energy of an object changes, there is inevitably some other change in energy at the same time.
PS3.C When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object.

Science Assessment

Item AP013005: Make observations to produce data to serve as evidence of energy transfer and write an explanation for why balls in a Newton’s cradle eventually stop moving.