## Simulation Scenario

Try using the TRE Simulation scenario as it was administered to students in the study (requires Flash 5 plug-in and may take up to two minutes to load). The text below is intended to describe the interface for users who cannot access the Simulation scenario in Flash.

### Simulation Interface and Tutorial

After responding to a set of prior knowledge questions, students were presented with the Simulation scenario introductory pages. The pages described the purpose of the Simulation scenario generally, what kind of simulation tool the students would be working with during the course of the scenario, and how students would be working with the tool. Students were told that they would be solving three simulation problems. “Back” and “Next” buttons on the lower right-hand side of the screen allowed students to navigate among the Simulation scenario pages, so they could review the introductory pages.

Moving at their own pace (with the understanding that they had 60 minutes to complete the scenario), students were given some definitions and conditions to keep in mind as they proceeded. Students were told that the simulated scientific helium balloon they were working with carries equipment called a "payload" that collects information about the environment and conditions in space. They were also told that the balloon could hold a maximum volume of 3,083 cubic feet of helium.

Next, students were guided through a tutorial that introduced them to each component of the Simulation tool interface. They were then directed to run an experiment and make a prediction about the results, with the option of repeating the various steps of the tutorial. (Note that the screen clearly indicated “Practice” in the upper left-hand side, so students knew they were not yet being scored for their performance.)

The simulation tool interface in many ways resembled instructional software and simulation games students might already have encountered. For example, the top of the interface featured a task bar for designing, running, and interpreting experiments, and the “Back” and “Next” buttons enabled students to navigate among screens.

The problem to solve was always displayed in the upper right-hand corner. The practice problem presented in the tutorial section was as follows:

How do different payload masses affect the altitude of a helium balloon?

To design an experiment to explore this relationship, students clicked on the Choose Values button in the Design Experiment task bar area. They could then make a prediction about the results of the experiment. Although making predictions was optional, the interface alerted students that they could not make predictions without having first chosen values for experiments. When students were ready to run an experiment, clicking Try It on the task bar caused the instrument display to activate and caused the balloon in an animated display, or flight box, to rise or remain stationary, depending on the value of the payload mass chosen.

Students were able to watch the balloon inflate and rise in the flight box, and could observe changes in the values of dependent variables (altitude, balloon volume, and time to final altitude) in the instrument panel below that box. Values for the independent variables (payload mass and amount of helium) were also displayed in the instrument panel.

Students could construct tables or graphs if they wished to keep track of experimental results by clicking on the appropriate task bar buttons under Interpret Results. The interface then presented results for all experiments run to that point.

When students were ready to draw conclusions based on their experimentation, they clicked on the Draw Conclusions button on the task bar under Interpret Results to bring up a text window where they could enter a response to the question featured on the upper right-hand part of the screen. Students could continue to experiment and use tables and graphs while they responded to the question.

Buttons in the lower right-hand corner offered three forms of help. These buttons brought up a Glossary of science terms, Science Help, and Computer Help. Science Help gave hints about the substance of the problem. Computer Help described the buttons and functions of the simulation tool interface.

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### Simulation Problem 1

After students completed the tutorial, they were asked to complete the problem presented in the tutorial on their own for Simulation problem 1. The problem read as follows.

For problem 1, you will use the simulation tool to experiment by changing the mass of the payload the balloon carries. The balloon is partially filled with 2,275 cubic feet of helium. (Remember: the balloon cannot hold more than 3,083 cubic feet of helium.) You will use the tool to solve this problem:

How do different payload masses affect the altitude of a helium balloon?

Think carefully about what experiments to run to help you solve the problem.

In the first problem, the only available independent variable was payload mass, and the values of mass that the student could select were restricted. (The balloon held a constant amount of 2,275 cubic feet of helium.) These constraints were imposed because of assessment time limitations and concern that the problem might otherwise be too difficult for significant numbers of eighth-graders. Note that the directions reminded the students that the balloon could hold only 3,083 cubic feet of helium.

After choosing a value for the payload mass, students could choose to make a prediction. By comparing the current experiment to the previous one, the options were intended to encourage students to think in terms of patterns of results: in this case, how varying the payload masses affected the altitude of the balloon.

To help interpret data, students could make a graph, a table, or both. Clicking on the Make Graph button on the task bar opened a dialog box that asked students to select a variable for the vertical axis and then, in a subsequent screen, for the horizontal axis. Note that students had leeway to get into trouble, as they could choose less relevant or incorrect variables for either graph axis; this design allowed an opportunity to determine whether students created interpretive tools related to the problem they were supposed to be solving.

Similarly, students could construct a table by choosing from the variables tracked in the instrument display on the flight box. The resulting displays, therefore, might contain relevant information, some relevant and some irrelevant information, or only irrelevant information. If, for example, a student chose to include all five variables, the table would show Payload Mass, Amount of Helium, Balloon Volume, Time to Final Altitude, and Altitude. A more helpful table for problem 1 might be limited to the dependent and independent variables necessary to solve the problem—altitude and mass. For each subsequent experiment that students chose to conduct, a line of data was added to the table automatically. Students could sort the table on any variable by clicking on the appropriate table column heading.

The relationship to be discovered in problem 1 was a virtually linear negative one: as mass increases, the altitude the balloon can achieve decreases. Proficient students would have been expected to conduct enough experiments, and spread the range of masses sufficiently, to confirm this relationship. (Note that in the context of TRE performance, the term “proficient” is used to mean “skilled” or “capable,” and does not denote the NAEP Proficient achievement level.) Too few values or too narrow a spread would have failed to confirm with sufficient certainty that the underlying relationship was linear throughout the range of masses.

When ready, students could click on the Draw Conclusions button on the task bar to bring up a text-entry box. This box called for students to construct a response to the question about the relationship between payload mass and altitude and to support the answer with experimental observations. Before completing the response, students could choose to revisit an existing table or graph, construct new tables or graphs, or conduct more experiments.

Having completed their written responses, students were required to respond to a multiple-choice question, which provided an alternative measure for those individuals unable to express their understanding of the mass-altitude relationship in writing. The multiple-choice question was as follows:

Based on your experiments, which statement most accurately and completely describes how different payload masses affect balloon altitude?

A. The less the payload mass, the lower the altitude reached by the balloon.

B. The greater the payload mass, the lower the altitude reached by the balloon.

C. Changing the payload mass does not change balloon altitude.

D. Increasing payload mass increases balloon volume and therefore balloon altitude.

E. The greater the payload mass, the greater the altitude reached by the balloon for any amount of helium.

F. The less the payload mass, the greater the altitude reached by the balloon for any amount of helium.

The correct answer is B; the greater the payload mass, the lower the altitude reached by the balloon.

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### Simulation Problem 2

Simulation scenario problem 2 asked students to determine the relationship between the amount of helium put in the balloon and the altitude that the balloon could reach. This time, the payload mass the balloon carried was fixed. Problem 2 read as follows:

How do different amounts of helium affect the balloon's altitude?

Problem 2 was conceptually more difficult because the relationship students had to discover was not linear. Rather, the relationship took the form of a step function. That is, until a critical amount of helium was put in the balloon, the balloon did not leave the ground. Once that critical amount of helium was achieved, the balloon would rise to a maximum altitude, then go no higher regardless of how much more helium was put into it, as shown in the graph in the figure below. To recognize the relationship, students had to choose a sufficient number and range of values and not draw conclusions prematurely; a premature conclusion would lead them to assume falsely either that the balloon would not rise at all or that it would continue to rise higher as it was filled with more helium.

As in problem 1, after completing their experiments students could draw conclusions by answering the constructed-response and multiple-choice questions. The text of the multiple-choice question was as follows:

Based on your experiments, which statement most accurately and completely describes how different amounts of helium affect balloon altitude?

A. The less the payload mass, the greater the altitude reached by the balloon.

B. The greater the amount of helium in the balloon, the greater the altitude reached by the balloon.

C. Changing the amount of helium in the balloon changes balloon volume but does not affect balloon altitude.

D. Changing the amount of helium does not affect altitude until there is enough helium in the balloon to lift the payload mass, after which the more helium placed inside the balloon the higher the balloon rises.

E. Changing the amount of helium does not affect altitude until there is enough helium in the balloon to lift the payload mass, after which the balloon rises to a maximum altitude and no higher.

The correct answer is E, changing the amount of helium does not affect altitude until there is enough helium in the balloon to lift the payload mass, after which the balloon rises to a maximum altitude and no higher.

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### Simulation Problem 3

Problem 3, the final simulation problem, was the most conceptually complex, as it required students to discover how payload mass and amount of helium worked together to determine the altitude that the balloon could reach. Problem 3 read as follows:

How do the amount of helium and payload mass together affect the altitude of a helium balloon?

Thus, students not only had to think about which experiments to run and how many, but also had to demonstrate an ability to control for one independent variable while manipulating the other. To limit the complexity of the problem, the number of masses students could vary was reduced to three.

In problem 3, students had to discover a nonlinear relationship that took the form of a series of step functions, one for each mass. Note that the maximum altitude for each step function decreased as payload mass increased, as shown in the graph in the figure below.

As with the two previous problems, students could draw conclusions by responding to the constructed-response question and answering a multiple-choice question. The text of the multiple choice question was as follows:

Based on your experiments, which statement most accurately and completely describes how different amounts of payload mass and helium together affect balloon altitude?

A. The less the payload mass, the greater the altitude reached by the balloon for any amount of helium.

B. The greater the amount of helium in the balloon, the greater the altitude reached by the balloon for all payload masses.

C. The greater the amount of helium in the balloon, the greater the altitude reached by the balloon up to the maximum altitude for all payload masses.

D. The less the payload mass, the more helium required to lift the mass, and the lower the maximum altitude reached by the balloon.

E. After enough helium is in the balloon to lift the payload mass, the balloon rises to a maximum altitude and no higher, and that maximum altitude is lower the heavier the payload mass.

F. After enough helium is in the balloon to lift the payload mass, the balloon rises to a maximum altitude and no higher, and that maximum altitude is higher the heavier the payload mass.

The correct answer is E, after enough helium is in the balloon to lift the payload mass, the balloon rises to a maximum altitude and no higher, and that maximum altitude is lower the heavier the payload mass.

When students finished entering their constructed responses and answering one multiple-choice question for problem 3, they were asked to respond to three additional multiple-choice questions to see how well they grasped the physics behind the Simulation scenario. To respond to these questions, students needed to have grasped that, short of increasing the size of the balloon, the only way to get the balloon to achieve a higher altitude would be to attach a payload mass smaller than any of the masses available to students in the Simulation.

After completing the synthesizing questions, students could read an explanation of the physics behind helium balloons, but they could not reenter the scenario after reading this explanation. The explanation was included because the TRE project team believed it was important that students leave the scenario with an accurate description of the science underlying the questions they had addressed. Finally, students responded to background questionnaires, as students did at the conclusion of the Search scenario.

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Read about the Search scenario.

For more information, see the Technology-Rich Environments overview page.

Last updated 02 July 2007 (RF)