You have some new experience testing boats. Because of your skills, a company has asked for your help. The company makes both watercraft, such as boats, and spacecraft, such as rockets. The company has offered to give you additional training so you can help it with a new project.
In this Explain activity, To Be Fair ..., you will learn more about fair tests. You will help the company decide on a new product line based on what you learn about testing. Materials
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Read the letter from the president of ABC Water and Space, Inc. This letter will help you understand what you will be doing in this activity.
Letter
Class,
I heard that you have been working on testing boat parts. My company makes watercraft. We make many different kinds of boats, from sailboats to cruise ships. We also specialize in spacecraft, like rockets and satellites. At the moment, we are trying to hire several new people. Until we get these new people hired, we need some help from you.
We are hoping to start a new product line of parts for our boats. We are also working toward having environmentally friendly products. We do not want to harm the environment. We do tests regularly to make sure our products do not lower water quality and to check other environmental issues (see figure 3-5). As part of our plan to find new products, we have been taking applications from smaller companies. These companies have a product that they want to sell to us to put in our product line. We have narrowed our choices down to the top three products.
Figure 3-5: This scientist is recording the results of her test. You will need to determine which of the companies used fair tests so that ABC Water and Space can decide on a new product.
We would like you to help us select the final product. The applications give details about how the smaller companies have tested their products. We would like you to help us determine which of the companies used fair tests. All the products have good test results, so we want to make sure the tests were fair. This should give us reliable results about the product. We need this information to choose the new product we will sell.
As part of your work, you will need to learn more about fair tests. We have provided you with information on fair tests. We also sent you a checklist to use as you choose the product. Finally, we would like you to give us evidence about why you selected your top choice. You will find all the forms and information you need in the packet we sent.
Sincerely,
Donald Ablestein
President, ABC Water and Space, Inc. -
Read the Applications master. It contains parts of the applications from ABC Water and Space’s three top choices. Underline or highlight any information that might help you make a decision about the product that the company should sell. Hint
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Read the additional information below, Fair Tests, which Donald Ablestein has sent to you. As you read, answer the questions in the hints. Also, add any words in bold or any unfamiliar words to your personal glossary. Hint
Fair Tests
Class,
I want to give you some more information about fair tests. By definition, a fair test is one that does not show any favoritism in the results. In a fair test, all elements that are being tested must be treated the same.
Consider this example of a test. In our company, one of the things we do is to test materials for rockets and boats. In one test, we wanted to find the best kind of foam insulation to go on the outside of a rocket. Foam insulation is important to rockets because it keeps the oxygen and hydrogen tanks on the outside from heating up too much. It can also keep ice from forming on the tanks before the rocket is launched. You can see the tanks in figure 3-6. Oxygen and hydrogen are very cold liquids. In the past there have been problems with foam insulation falling off rockets. In this test, our company engineers wanted to find out which kind of foam insulation was best.
Figure 3-6: Foam insulation helps keep the tanks on the outside of rockets from heating up too much. It also helps keep ice from forming on the tanks.
The engineers tested four different kinds of foam insulation. They attached the foam to four different oxygen tanks. Then the engineers put the tanks with foam 1 and foam 2 in freezers with different cold temperatures and left them there for a week. They put the tanks with foam 3 and foam 4 in ovens with different hot temperatures and also left them there for a week. After the week was up, the engineers took the four types of foam off the tanks. They looked at whether the foam had broken apart in the different temperatures. They concluded that, based on this test, foam 1 and foam 2 were better because they did not show any signs of breaking apart. Hint
You probably noticed that there were several different factors involved in the test. There were different kinds of foam. There were tanks. There were different temperatures, both hot and cold. There was the length of time the foam was tested. After the test, the foam was studied to determine whether it broke apart. Each of these factors is called a variable.
There are different types of variables to think about when you are doing an investigation. One type of variable is called the independent variable. The independent variable is what you are changing in your experiment. You might also think of it as what you are testing. Hint
There is also the dependent variable. The dependent variable is what you are observing in your investigation. It depends on or responds to what you change in your investigation. Hint
Some of the variables should be kept the same in your test. These are all the variables that you are not testing. You should do everything you can to keep them constant. Keeping all the variables the same except for the one you are testing is what makes a test fair. Hint
Another thing to think about when you are testing is how to determine that the results are due to your experiment. What if the foam broke down after a week even if it was sitting at room temperature? How would you know that? To help solve that problem, many experiments need a control. A control is what you use to compare the tests. It is almost the same as what you are testing except that the independent variable does not change. Not all experiments have a control. It is not always possible to keep all the other variables constant when you are doing an experiment. That does not mean the test is not fair.
A final thing to consider when you are testing is how many times you try the test. If you only do one test, are you sure that the results are correct? You usually need to try a test a few times to make sure you get similar results each time.
Since our original foam insulation test, we have started paying much more attention to fair testing. If we were going to do that experiment today, we would do some things differently. We would make sure that all four types of foam sat at the same temperature in each test. Remember, in our earlier test, two types were at a cold temperature and two types were at a hot temperature. We also would have several pieces of foam on different tanks so that we would be testing more than one sample. We would make sure that more pieces of foam sat at room temperature for the length of the test. That way we would know that any breakdown was due to the cold or heat, not just because the foam falls apart after a week.
I hope this information helps you as you review the boat product testing. We want to be confident of the test results, so we are very concerned about making sure that fair tests were run. Because of that, your work is very important to us.
Donald
Donald Ablestein also provided a checklist for the tests. You will return the completed checklist to ABC Water and Space as evidence for your choice. Read the questions on the Fair Test Checklist 1 master.
With your team, use information from the Applications master to fill out Fair Test Checklist 1. Hint
In the “additional comments” section of Fair Test Checklist 1, write a paragraph for Donald Ablestein that explains which product his company should sell. Remember, he is interested in selling the product that has the most reliable results. To have reliable results, the tests have to be fair. Hint
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In the Explore activity, you tested a part of a boat. Join with a team that tested a different boat part. Then follow Steps 7a–d.
- Take turns explaining your team’s test to the other team.
- Ask any questions you might have so that you understand the test the other team ran.
- Complete the Fair Test Checklist 2 master to determine whether the other team ran a fair test. Hint
- In the “additional comments” section, make a list of anything the other team would need to change to make its test fair.
Activity Overview
In this Explain activity, To Be Fair ..., students will learn about fair tests through work with a fictitious company. The company is adding a new product line. It has received applications from smaller companies that detail how those companies tested their products. Students will use what they learn about fair tests to determine the most reliable test results and choose the new product.
Before You Teach
Background Information
Conducting a fair test is probably one of the most important processes in scientific investigations and technological design, and it is one of the most difficult to do in all situations. Students might understand the concept of a fair test but still have difficulty carrying out a fair test in every situation. For example, in the tests in the Explore activity, they may have changed more than one variable or merely estimated the distance the boat traveled. Remember that students were not expected to run fair tests during that activity, so there may be other problems with the tests as well.
In this Explain activity, the reading refers to independent and dependent variables. Your school or district may use the terms manipulated and responding variables. If so, introduce these terms to students at the same time to explain that the independent variable is the same as the manipulated variable and the dependent variable is the same as the responding variable.
Materials
For each class of 30 students:
- 30 copies of Master 3-5, Applications
- 30 copies of Master 3-6, Fair Test Checklist 1
- 30 copies of Master 3-7, Fair Test Checklist 2
- 1 copy of the letter in Step 1
Advance Preparation
Make 30 copies of Master 3-5, Applications. The activity begins with a letter from the president of a fictitious company. You may wish to begin class by opening an envelope, then reading the scenario. If so, you will want to place a copy of the letter in an envelope before the start of class.
As You Teach
Outcomes and Indicators of Success
By the end of this activity, students will
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understand what it means to conduct a fair test.
They will show their understanding by
- choosing a test that was run fairly from three applications
- explaining how they could improve the boat testing from the Explore activity
- describing the components of a fair test from an example.
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be able to describe the importance of conducting fair tests.
They will show their understanding by explaining why the company wants to sell products that were tested fairly.
Strategies
Getting Started
Begin class by opening the envelope and reading Donald Ablestein’s letter aloud during Step 1 of the activity.
Process and Procedure
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Complete Step 1 as described in the Getting Started section.
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As described in the letter, the Applications master provides information about the three products from the small companies. Make sure students realize that the identifying information about the companies is not shown, so they have only the information on the Applications master to use in their decisions. Also emphasize that Donald Ablestein, the president of the fictitious ABC Water and Space Inc., wants help choosing the product that was tested using fair tests (as mentioned in the hint) so he will know that the results are reliable. As students read, have them underline or highlight information that may help them make a decision, but remind them that they are going to learn more about fair tests. If they are not sure, it is okay to not underline anything at this point.
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Have students read Fair Tests, which is in the form of another letter from Donald Ablestein. As they read, students should add any bold or unfamiliar words to their personal glossaries. As stated in the hint, How to Develop a Personal Glossary will remind them of how they should make their entries. The teacher version of How to Develop a Personal Glossary can be found at this link. There are a number of important words related to fair testing in this reading, so it is important that students begin to gain an understanding of them through the entries in their personal glossaries.
Answers to the tasks in the reading
Is this a valid conclusion? In other words, was this a fair test of the foam? Why or why not? In deciding your answer, go back to the definition of a fair test.
Students may still have different ideas at this point because they have not yet read about fair tests. If they look back at the definition of a fair test in the first paragraph, many students will realize that this was not a fair test because not all of the types of foam were treated the same.
What is the independent variable in the foam investigation?
The independent variable, or manipulated variable, is the type of foam. This is the variable that was changed in the experiment.
What is the dependent variable in the foam investigation?
The dependent variable is whether the foam broke down. This is also called the responding variable. In this case, whether the foam broke down “depended on” the type of foam.
What variables should the engineers have kept constant in the foam investigation?
The variables that should have been kept constant include the temperature, the type of tank, and the length of time that the tanks were exposed to the different temperatures.
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Have students use Master 3-6, Fair Test Checklist 1, as evidence for Donald Ablestein to justify their choice of products. Have them read the questions, and make sure they understand what they are supposed to do.
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As a team, students should work to complete Fair Test Checklist 1. All team members should complete their own checklist. Have students read the hint and emphasize that they should place the evidence for their answers in the “comments” column, and that every row should have an entry in that column. These comments will help Donald Ablestein to determine whether they completed the work and understood why they made the choice they did.
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In the Additional Comments section of Fair Test Checklist 1, students should write a paragraph to explain their final decisions about which product they have chosen. They should explain how the tests for that product were fair.
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Step 7 has students think back to the boat tests they completed in the Explore activity. At that point, they probably did not know much about fair tests. Remind them that they were not expected to conduct a fair test, so they should not be made to feel that they performed the activity incorrectly. Students should partner with another team that tested a different method of moving the boats (sails, propellers, or fuel) than their team did. They should explain the tests they conducted and allow the other team to clarify any information about those tests. Have students complete the table in Master 3-7, Fair Test Checklist 2. This table is the same as the table in Fair Test Checklist 1, so students should have a reasonable understanding of how to complete it. Remind them again that all “comments” cells should contain evidence. In the Additional Comments section, they should list anything the other team must change to make its tests fair.