Science Assessment ~ Items ~ AP038006

A student wants to build a catapult. A catapult is a device that can be used to launch an object into the air. To learn more about how catapults work, he makes a simple catapult. He holds a flat wooden stick at the edge of a table, places a small ball at the end of the stick, and pulls the end of the stick down before releasing it. The video below shows what happened.

The figure below shows a diagram of the ball and stick when he bends the stick (Time 1) and when he lets go (Time 2). He wants to use what he knows about energy to explain how the catapult works and figure out how to get the ball to go as high as it can.

1. He thinks about how the kinetic energy of the ball and the potential energy of the stick change when the ball is shot into the air. The bar graph below shows the amount of energy the stick and ball have while the ball is sitting on the bent stick (Time 1).

Create a bar graph to show the amount of energy the stick and ball have just as the ball starts moving up and the stick is no longer bent (Time 2).

[Students Model]

2. Where does the ball get the energy to shoot up into the air when the stick is released? Explain your answer using ideas about energy transfer and evidence from the video.

After testing his simple catapult, he wants to find out if the amount the stick is bent could affect how high the ball goes into the air. He designs a simple experiment to help him answer that question. He thinks he should use the same stick and ball throughout the experiment.

3. Why is it important that the ball be the same throughout the experiment?

A. By using the same ball, you can learn which type of ball goes higher when shot into the air.

B. By using the same ball, you can learn how the amount the stick is bent affects how high you can shoot the ball into the air.

C. By using the same ball, you can learn two things. You can learn which type of ball goes higher when shot into the air. You can also learn how the amount the stick is bent affects how high you can shoot the ball into the air.

D. It is NOT important for the same ball to be used. Even if you use different balls throughout the experiment, you can still learn how the amount the stick is bent affects how high you can shoot a ball into the air.

4. What variable should he change during the experiment?

5. If you were to do this experiment, under what condition would you expect the ball to go the highest?

6. Why do you think the ball would go the highest under this condition? Explain using what you know about energy.

Details
Performance
NGSS

Topic: 3D Energy Tasks
Scoring Rubric: Q1; Student draws bars on the graph

For the potential energy of the stick, a bar of zero height (or no bar)

AND

For the kinetic energy of the ball, a bar of some height

Note: If a student draws a bar for the potential energy of the stick, the important thing is that the bar for Time 2 must be shorter than the bar for Time 1. (These students may have chosen a different zero point for potential energy.); Q2; 1. Student makes a claim about the energy source

The ball gets energy from the stick.

2. Student cites evidence

The stick goes from being bent to being straight.

3. Student either states or uses a general science idea

Bending an [elastic] object increases the potential energy on the object (i.e., the more the stick is bent the more energy it has). [links bending and energy]

Energy is transferred when one object exerts a force on another object (i.e., the stick pushes the ball transferring energy to the ball). [links force and energy transfer]

When the motion energy of an object changes, there is inevitable some other change in energy at the same time (i.e., the motion energy of the ball changed and thus there must have been changes in energy elsewhere). [conservation]

4. Student uses a crosscutting concept

Energy may take different forms (e.g., the potential energy of the stick is transformed into the kinetic energy of the ball). [forms of energy]

The transfer of energy can be tracked through a system (e.g., energy is transferred from the stick to the ball or, the energy came from the stick, or the stick gave the ball energy). [energy can be tracked]

5. Student uses reasoning to link evidence, science ideas, and/or crosscutting concepts to the claim

The stick exerts a force on the ball when it is let go and the force transfers energy from the stick to the ball.

OR

The stick decreases in energy because it goes from being bent to being straight and because the stick interacted with the ball, the energy is transferred from the stick to the ball.; Q3; Student selects answer choice B

B. By using the same ball, you can learn how the amount the stick is bent affects how high you can shoot the ball into the air.; Q4; Student states the independent variable

The amount the stick is bent.

OR

The amount of force applied to the stick.

OR

The potential energy of the stick.; Q5; Student makes the correct prediction

The ball would go the highest when the stick is bent the most.; Q6; 1. Student either states or uses a general science idea

Bending an [elastic] object increases the potential energy on the object (i.e., the more the stick is bent the more energy it has). [links bending and energy]

Energy is transferred when one object exerts a force on another object (i.e., the stick pushes the ball transferring energy to the ball). [links force and energy transfer]

2. Student uses a crosscutting concept

The transfer of energy can be tracked through a system (e.g., from the stick to the ball). [energy can be tracked]

Energy may take different forms (e.g., the potential energy of the stick is transformed into the kinetic energy of the ball). [forms of energy]

3. Student uses reasoning to link science ideas and/or crosscutting concepts to their prediction

The more the stick is bent, the more energy it has that can be transferred to the ball when released. The more energy the ball receives from the stick, the higher it will go.

Percent of Points Earned

Chart showing distrubtion of responses for Item AP038006

Points Earned

	Avg. Earned	Possible	Percent
Q1	0.42	1	42%
Q2	1.13	5	23%
Q3	0.47	1	47%
Q4	0.32	1	32%
Q5	0.52	1	52%
Q6	0.47	3	16%

Overall Task Difficulty

	Total Points Earned	Total Points Possible	Total Percent
	3.33	12	28%

n = 230

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 Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.
SEP4 Construct, analyze, and/or interpret graphical displays of data and/or large data sets to identify linear and nonlinear relationships.
SEP6 Apply scientific ideas or principles to design, construct, and/or test a design of an object, tool, process or system.
SEP7 Construct, use, and/or present an oral and written argument supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem
Crosscutting Concepts: CC2 Cause and effect relationships may be used to predict phenomena in natural or designed systems.
CC5 Energy may take different forms (e.g. energy in fields, thermal energy, energy of motion).
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.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 AP038006: Design an experiment to determine how the amount a stick is bent affects how high a ball can be shot into the air and construct an argument for which trial will result in the ball traveling the highest using cause and effect relationships and ideas about energy. (CR version)