Science Assessment ~ Items ~ AP030006

As a science project, a girl builds a device to create water droplets. The device is made of a water bottle that has been cut into two sections. She takes the top section of the bottle and flips it over so that it sits inside the bottom section as shown below.

She places water at 0 °C in the top section and an equal amount of water at 100 °C in the bottom section. After placing the hot water in the bottom section, she leaves a space between the top and bottom sections. That middle section is empty except for air and water vapor. A diagram of the girl’s device is shown below.

After a few minutes, water droplets form on the outside surface of the top section.

The girl notices that water droplets stop forming after an hour, and eventually all the water droplets disappear.

The girl thinks that this is due to changes in the temperature of the water in each section of the device. She refills the device with water at 0 °C and 100 °C, but this time she records the temperature of the water in each section every five minutes. Below is a plot of her data.

1. Describe the patterns you observe in the data for the temperature of water in the top and bottom sections of the device.

2. Which of the following best describes how energy was distributed during the experiment?

A. Energy was transferred from the hotter water in the bottom section to the colder water in the top section until the energy was distributed evenly between the water in the top and bottom sections.

B. Energy was transferred from the hotter water in the bottom section to the colder water in the top section, but the energy never became evenly distributed between the water in the top and bottom sections.

C. Energy was transferred from the colder water in the top section to the hotter water in the bottom section until the energy was distributed evenly between the water in the top and bottom sections.

D. Energy was transferred from the colder water in the top section to the hotter water in the bottom section, but the energy never became evenly distributed between the water in the top and bottom sections.

The girl wants her device to continue to produce water droplets. So, she decides to add a heating coil that will heat the water in the bottom section of the device to keep its temperature at 100 °C.

3. Draw a graph representing how you think the temperature of the water in the top of the device will change if the temperature of the water in the bottom section is kept at 100 °C.

[drawinginput]

4. The girl believes that keeping the water in the bottom part of the device at 100 °C will cause the device to continue to produce water droplets in the middle section.

Write an argument for or against the idea that the device will continue to produce water droplets as long as the heater is on and the the water in the bottom section is kept at 100 °C. Support your argument using the graph you created, evidence from the girl’s previous experiments, and what you know about energy transfer. Clearly state any assumptions you are making in your argument.

Details
Performance
NGSS

Topic: 3D Energy Tasks
Scoring Rubric: Q1; Student describes the following patterns in the graphed data

The temperature of the water in the bottom section of the device decreased over time.

The temperature of the water in the top section of the device increased over time.

Eventually, the water in the bottom and top sections reach the same temperature.

Note: Describing the temperature changes as the temperatures converging or coming together/to equilibrium is acceptable for all three bullets.; Q2; Student selects answer choice A

A. Energy was transferred from the hotter water in the bottom section to the colder water in the top section until the energy was distributed evenly between the water in the top and bottom sections.; Q3; Student's graph includes the following elements

Temperature of the top section starts at 0°C

Temperature of the top section increases over time

Temperature of the top section of water equilibriates to 100°C; Q4; 1. Student makes the correct prediction

The revised design will eventually stop producing water droplets.

2. Student cites evidence and/or uses their graph to support their argument

The graph shows that the temperature of the water in the top section will gradually increase until it reaches 100°C.

Note: Student must mention the graph to get this point.

The previous experiment showed that the droplets will stop forming once the temperature of the water in the sections becomes equal.

3. Student either states or uses a general science idea

Energy is spontaneously transferred out of hotter regions or objects and into colder ones (i.e., energy will be transferred from the hotter bottom section to the cooler top section). [Conduction]

Note: Student must use the word energy to get this point.

When a warmer object is touching a cooler object, the warmer object gets cooler and the cooler object gets warmer until they are at the same temperature at which point the temperature won't change anymore (i.e., the temperature of the top section will increase until the temperature of the water in the sections reach equilibrium). [thermal equilibrium]

Uncontrolled systems always evolve towards more stable states - that is, towards more uniform energy distributions within the system (i.e., energy will be transferred from the bottom section to the top section until the energy is equally distributed between the sections). [uniform energy distribution]

4. Student supports their prediction with reasoning that links the evidence and science ideas

The difference in temperature was causing the water droplets to form, so if there is no temperature difference, water droplets will no longer form.

OR

The transfer of energy from the bottom section to the top section was causing the water droplets to form, so if there is no energy transfer, water droplets will no longer form.

Student uses productive ideas not represented above [not scored]

Student references the effect the ambient temperature will have on the temperature of the water in the device.

Percent of Points Earned

Chart showing distrubtion of responses for Item AP030006

Points Earned

	Avg. Earned	Possible	Percent
Q1	1.09	3	36%
Q2	0.42	1	42%
Q3	1.02	3	34%
Q4	0.44	4	11%

Overall Task Difficulty

	Total Points Earned	Total Points Possible	Total Percent
	2.96	11	27%

n = 233

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: SEP4 Construct, analyze, and/or interpret graphical displays of data and/or large data sets to identify linear and nonlinear relationships.
SEP7 Construct, use, and/or present an oral and written argument or counter-arguments based on data and evidence.
SEP8 Communicate scientific and/or technical information or ideas (e.g. about phenomena and/or the process of development and the design and performance of a proposed process or system) in multiple formats (i.e., orally, graphically, textually, mathematically).
Crosscutting Concepts: CC1 Graphs, charts, and images can be used to identify patterns in data.
CC7 Some systems appear stable, but over long periods of time will eventually change.
Disciplinary Core Ideas: PS3.B Uncontrolled systems always evolve toward more stable states--that is, toward more uniform energy distribution (e.g., water flows downhill, objects hotter than their surrounding environment cool down).

Science Assessment

Item AP030006: In a device that creates water droplets by condensing water vapor, analyze data to make a prediction about whether the device would continue to produce water droplets if one section is kept at a constant temperature. (CR Version)