Name: ______Date: ______Period: ____
Finding the Answer
Did you ever have to find an answer to a problem? You may have used a method known as trial and error. This process of random guessing is often used to find the missing piece for a jigsaw puzzle. However, you may have used a more scientific method to answer your problem.
A detective uses the same steps to investigate a crime that a scientist uses in an experiment. The detective begins by observing the clues of the crime. Using these observations, the detective makes an educated guess or hypothesis regarding possible solutions to the crime. The hypothesis must be proven or rejected before the detective can charge someone with the crime. So, a way to test the hypothesis is designed. More evidence is gathered. On the basis of all evidence, the detective comes to a conclusion that the original hypothesis was right or wrong.
Logical steps must be followed to test a hypothesis in order to develop correct conclusions. Often, a control is used to compare results. A control is an exact model of the test situation. However, in the control, none of the factors vary.
After sufficient testing, the hypothesis is found to be true or false. The final conclusions are now called a theory. Many scientific theories exist to explain the behavior of the universe.
Strategy
You will recognize observations, hypothesis, and conclusions.
You will make and test your own hypothesis.
You will compare an experimental situation to a control.
You will decide whether the conclusions you draw support or deny your hypothesis.
You will use your conclusions to develop a theory.
Materials
metric ruler, scissors, tape, pencil, 2 paper strips (25cm x 3cm)
Procedure
Part A: Comparing Two Paper Models
1. Tape the two ends of one paper strip together to form a circle. Take the other strip of paper and bring the two ends together. Before you tape the ends, take one and twist it over once. Now tape the ends together.
2. Examine your models carefully. One should be an ordinary circle. The other is a special cind of circle with one twist in it called a Mobius Strip.
3. Make your first hypothesis based on the following question. What do you think will happen if you start to draw a line down the center of the paper models without lifting your pencil? That is, what happens when you hold the pencil against the paper and gently pull the model so the pencil marks it? Decide what will happen and write a hypothesis for each model before you actually do it!
circle - ______
mobius strip - ______
4. Test your hypothesis by drawing the lines. Record your observations. Then, based upon your observations, make a conclusion.
Circle observations - ______
conclusion - ______
Mobius strip observations - ______
conclusion - ______
5. Now, make a second hypothesis based on the following question. What do you think will happen if you cut the models along the lines you have drawn?
Circle hypothesis - ______
Mobius strip hypothesis - ______
6. Test your hypothesis. Cut the paper models along the lines. Be careful to cut only along these lines. Make a conclusion using reasoning to explain your observations.
Circle observations - ______
conclusion - ______
Mobius strip observations - ______
conclusion - ______
7. Make a third hypothesis based upon the following question. What do you think will happen if you cut the models along the center again?
Circle hypothesis - ______
Mobius strip hypothesis - ______
8. Test your hypothesis by cutting the models along the center again. Be careful, there are no lines to guide your cuts this time. Record your observations. Then draw a conclusion to explain your observations. Does your conclusion agree with your hypothesis?
Circle observations - ______
conclusion - ______
agree with hypothesis? ______
Mobius strip observations - ______
conclusion - ______
agree with hypothesis? ______
9. Examine your results and compare them with the results of your classmates. Using everyone’s results, develop a theory for your class to explain what happened in this experiment.
circle theory - ______
______
______
mobius strip theory - ______
______
______
Part B: The Bank Robbery
The following story will make the process of problem solving used by scientists and detectives clear for you. Carefully read the story and identify the hypothesis, the data and the conclusions.
A man walked into the First National Bank, held up a gun, and demanded money. A teller filled a paper bag with money. At the same time, another teller carefully set off an alarm. The robber heard the alarm and fled from the bank, escaping on a purple motor bike.
When the police arrived at the bank, they questioned the tellers. The police discovered the robber wore a floppy green hat, sunglasses, gloves, and a pair of overalls. While searching the grounds around the bank, police found a gun and a green hat. No fingerprints were found on the gun. The green hat had the initials T.S. stitched in the brim. When the gun’s registration was checked, the police found that I belonged to a Tim Smith. A warrant was obtained to search the home of Tim Smith.
Tim Smith was not home when the police arrived. A neighbor told the police that Tim had been in the hospital with a broken leg for two weeks. When the police checked the hospital, they found the neighbor’s story was true. Tim Smith was not the robber.
During questioning, Tim Smith admitted owning a floppy green hat and a gun, but he didn’t know anything about a purple motor bike. He allowed the police to check his home, and they found it had been robbed. Among the missing items were Tim’s gun and green hat. The police checked for fingerprints and found prints belonging to John Thomas. The police searched the home of John Thomas and found a purple motor bike. In the basement they discovered a bag of money. John was taken to the police station for questioning. The tellers were unable to identify John Thomas as the robber. However, the serial numbers of the money found in John’s basement matched the serial numbers of the bank’s missing money. The police then had the evidence needed and charged John Thomas with bank robbery.
Questions:
1. List the evidence or data the police gathered before making any hypothesis about the identity of the bank robber.
______
______
2. State the first hypothesis the police made concerning the identity of the bank robber.
______
3. The police did not immediately request a warrant to arrest Tim Smith. Explain why.
______
4. List some evidence that was gathered but not used to form or test the hypothesis.
______
______
5. State the second hypothesis the police formed about the identity of the bank robber.
______
6. What evidence was used to test this hypothesis? ______
______
7. What conclusion did the police make about the bank robber’s identity? ______
______
Conclusions:
1. When you made the paper models, why was it important to read carefully and follow
the directions? ______
______
2. Why did it help to compare your observations and conclusions with your classmates?
______
______
3. Why do scientists publish the results of their work in scientific magazines?
______
______
4. What is the difference between superstitions and scientific theories?
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