Scientific Method Worksheet Answers

Scientific Method Worksheet Anyone who has ever read a mystery novel or seen a “whodunit” on TV, has seen the scientific method in action. Anyone who has ever tried to figure out what happens to the refrigerator light when you close the door, or where that other sock goes after you put it in the drier, has used the scientific method. The scientific method is not a mystical, incomprehensible rite that only “polyester plaid” science nerds use to solve esoteric problems. Instead, it is a logical, organized mechanism for identifying and researching a problem, and devising a strategy for solving it. The scientific method is split up into five major steps: 1. Determining the problem or question. - In this step, you (the researcher) must decide what it is that you will be studying. This sounds like a simple procedure, but it is actually very important. It identifies exactly what you wish to learn and it allows you to focus only on that material. 2. Development of a hypothesis. - The hypothesis is not a just a random W.A.G (Wild @$$#& Guess) to your problem. Instead, the hypothesis is an Educated Guess. In other words, it involves researching the problem and finding out what other people have learned, and using that information to help devise an answer. An important aspect of the hypothesis is that it should answer the original question, and it should be testable! 3. Design an experiment to test the hypothesis. - Design an experiment whose results will either support or disprove your hypothesis. If your hypothesis is supported, then the results of your experiment will indicate that your hypothesis is correct. However, this does not mean that your hypothesis is 100%, beyond a shadow of a doubt, correct. There may be other factors that will influence the results that you haven’t tested. Therefore, it is important to say that the hypothesis is supported, you should never say that it is proven! However, the results of your experiment can prove your hypothesis wrong! - There should be at least two groups in your experiment. The first group is the experimental group. This group is the group that has the factor that is being tested (Experimental Variable). It is easy to identify the experimental variable, since it is usually stated in the hypothesis. The second group is the control group. The control group is identical to the experimental group in every way, except that they lack the experimental variable. (If there were other differences, then they would invalidate the results of the experiment.) 4. Conduct the experiment and collect the data. - Run the experiment that you have so carefully constructed. In this step, you will be measuring the dependent variable. This variable (DO NOT confuse it with the experimental variable) is the thing that is being observed or measured. Any pieces of information that you collect regarding the dependent variable are called DATA. 5. Draw Conclusions from your data. - Here, it is stated directly whether the hypothesis was supported or disproven. - If your hypothesis is supported, it should be repeated, since one of the basic foundations of the scientific method is that it is repeatable. The more an experiment is repeated, the more valid the results are. However, if there is a hypothesis that is supported by many experiments and a lot of data, we call that hypothesis a theory. - The word theory is often misused in everyday language. Theory and hypothesis are not synonyms, a hypothesis is just an educated guess that perhaps has been supported once or twice by an experiment. A theory was once a hypothesis, but is now supported by a lot of data and is accepted as being correct, until new information is discovered to disprove it. 1 1. List the parts of the scientific method in order. 1. Determine the problem or question 2. Develop a hypothesis - possible answer to your question 3. Design an experiment to test the hypothesis 4. Conduct an experiment and collect/analyze the data 5. Draw conclusions from your data 2. What are dependent and experimental variables? The Experimental variable is the one being tested - otherwise known as the 'independent' or 'manipulated' variable. It is the one that you as an experimenter are in control of. The Dependent variable is the on that you are measuring or counting - the one that changes as a result of the other. 3. Suppose you are a researcher who is studying Pacific White-sided Dolphins (Lagenorhyncus obliquidens). While studying a captive group of dolphins at an aquarium, you notice a strange tendency for the dolphins to stay close to the surface shortly after being fed. You are intrigued, and after looking for more information, you learn that some species of dolphins will sometimes stay close to the surface when they have gas. Dolphins may normally feed on many species of fish in the wild, but you notice that the dolphins tend to stay close to the surface after being fed fish belonging to species “A”. Thus, you hypothesize that fish belonging to species “A”, gave the dolphins gas. Design an experiment to test this hypothesis. a. What is the hypothesis (Hint, it is already given)? Fish belonging to species A give the dolphin gas. b. Design an experiment to test this hypothesis, and use another sheet of paper if necessary. (Be sure you can explain how you are going to conduct the test, and predict what the results will be if they support the experiment.) You are not to create the data for your results section. One way to test is to have 2 groups of dolphins. Group A will receive fish from species A Group B will receive other fish - not from species A Observe whether any dolphins swim to the top. If dolphins in group A swim to the top and others don't, then hypothesis will be confirmed. 2 5. Niko Tinbergen (1907-1988) was a Swedish Ethologist (animal behaviorist) famous for studying animals in their native habitats. One of his classic experiments involved a bird called the black-headed gull (Larus ridibundus). Black-headed gulls build nests of twigs on the ground and lay light brown eggs that are covered with dark brown spots. However, the inside of the egg is white in color. Tinbergen noticed that adult gulls pick up the eggshells shortly after a chick has hatched, and fly them to a location far from the nest, where they are left. Since this behavior required expending energy and time that could have been spent feeding and protecting the chicks, Tinbergen wanted to know why the birds did this. Problem: Why do black-headed gulls remove eggshells from the nest? Hypothesis: The white interior of the shell is not camouflaged and attracts predators to the nest. Therefore, the gulls remove the shells to decrease predation. Test: Tinbergen and his co-workers collected gull eggs and painted 69 of them white and left 68 of them with their natural color. (Statistically, these numbers are close enough to be considered equal.) The researchers then scattered the eggs next to a gull breeding area and observed from a nearby blind. Predation rates were recorded for white versus natural colored eggs. Data: Original Number of Eggs Eggs Taken by Predators Eggs Not Taken ---------------------------------------------------------------------------------------------------------White Eggs 69 43 26 Natural Eggs 68 13 55 ---------------------------------------------------------------------------------------------------------a. Do the results of this experiment support the hypothesis? Why, Why not? Yes, it appears that the results do support the hypothesis because many more white eggs were taken by the predators than the natural ones. b. Are you 100% sure (without a doubt) that your hypothesis is correct? (Is it proven?) No, there is still some doubt because not 100% of the white eggs were taken, and more testing must be done. c. If you were working with Tinbergen, what would you suggest be done next? I would do further tests - repeat the experiment with more eggs, and in more places. d. Identify the experimental and dependent variables Experimental variable - colour of eggs Dependent variable - how many eggs were taken by predators. 4 6. The media has given a lot of attention recently to shark attacks on humans, due in part to several high profile incidents. Are the numbers of shark attacks becoming more frequent, or are we just hearing about them more often than before because of the previous cases in the news? The following chart was made using data from the ISAF (International Shark Attack File) a group that tracks shark attacks world-wide. Unprovoked shark attacks for World (light) and United States (dark) from 1960 through 2002. The drop in recorded attacks in 1969 (dashed-dotted line) is a result of a loss of funding to support the ISAF, and hence less effort reporting and organizing of attacks (see The History of the International Shark Attack File). The apparent increase in attacks after 1987 (dotted line) is in part an artifact of the ISAF moving to the Florida Museum of Natural History, resulting in an increased scope of coverage and reporting of attacks. The apparent increase in attacks after 1993 (dashed line) is in part an artifact of a breakthrough in communication with Volusia County (FL) emergency responders and lifeguards, resulting in the reporting of a greater number of minor attacks that had previously gone unreported. a. Do the data from this chart indicate that there is a general increase in the number of shark attacks? Do the data here tell us why this is happening ? The data does suggest that the number of shark attacks is increasing, but it does not tell us why. b. One hypothesis that attempts to explain these attacks, says that the increase is do to “shark feeding” programs introduced in the late 1980’s and used at vacation resorts to attract divers and snorkelers. People pay tour operators to put dead fish (chum) into the water to lure sharks, so that they can interact and sometimes feed the sharks. The hypothesis states that sharks become used to humans feeding them, and then bite other humans when they don’t get fed. Design an experiment to test this hypothesis on the next page. Be sure to identify the variables and the groups. 5 Question: Why is there an overall increase in the number of shark attacks? Hypothesis: Shark feeding programs are causing an increase in shark attacks. Conduct more surveys in areas that are known to feed sharks vs areas that are known for leaving sharks alone. Are there more attacks in the areas where sharks are being fed? Are there fewer attacks in the areas that don't feed sharks? Another bit of data you can use is track individual sharks - when a shark is fed, put a tracer on it, and watch to see if it attacks humans later. C. From the chart, it is obvious to see that there is an overall increase in the number of shark attacks, even though some years (such as 1996) have fewer than others. However, is it possible that some other factor may be influencing the results? One thing the chart doesn’t say is that many shark attacks occur in areas where there aren’t a lot of people, such as in Western Australia. With the introduction of the internet and cellular communication in the 1990’s, would you expect the ability of biologists to REPORT shark attacks to increase? Yes, as technology improves, so does the ability to report and record attacks in more areas. D. One problem with data like this is that it doesn’t always indicate other factors that might influence the results. This is why it is so necessary to repeat and continue to test hypotheses. The ISAF states on their web site that while this data is accurate, it doesn’t take into account the fact that human populations are increasing world-wide. With this increase in population, there are more people around, therefore there will be less habitat for the sharks to hunt for food (since humans are now living and playing on beaches not inhabited before). Could this increase in contact between humans and sharks result in more attacks. Yes, if there are more people in shark infested areas, it means that there are more targets for the sharks to go after. Also, as the human population increases, food supplies for the sharks decreases as the fish population declines, so sharks will go after the next best available food source. E. Does the chart now say the same thing to you that it did before? It is very important when looking at a study to be objective. You may be surprised to learn that not everything that you see on the internet or in the media is as it seems on the surface. In this class, we will learn to look objectively and think critically about information. 6 Biology 127 Introduction to Evolution Scientific Method Worksheet Name ____________________________________________ Date ____________________________ Write in the word or short phrase needed to answer the question or complete the statement in the space provided. This page will be torn off and turned in for homework. EXPERIMENTAL VARIABLE _________________________7. Give the general name for the factor that is tested in an experiment. ALSO KNOWN AS INDEPENDENT VARIABLE OR MANIPULATED VARIABLE DEPENDENT VARIABLE _________________________8. Give the general name for the factor that is observed, measured or ALSO KNOWN AS counted in an experiment. RESPONDING VARIABLE _________________________9. Which group contains the variable that is being tested? EXPERIMENTAL GROUP CONTROL GROUP _________________________10. Which group is identical the group above in every way EXCEPT for lacking the variable that is being tested? _________________________11. If a hypothesis is tested a number of times and supported each time, VALIDITY OR RELIABILITY the best term to describe the “correctness” of that hypothesis is: REJECTED OR DISPROVEN _________________________12. If a hypothesis is tested and found to be incorrect, then we say that the hypothesis has been: _________________________13. In question number 4 dealing with the tadpoles, which group (give the OMIT THIS QUESTION number) was the control group? _________________________14. In question number 4 dealing with the tadpoles, what was the OMIT THIS QUESTION experimental variable? YES _________________________15. In question number 5 dealing with the Black-headed gull, did the experiment support the hypothesis? (yes or no) IMPROVEMENTS IN THE ABILITY TO REPORT INCREASE IN HUMAN POPULATIONS IN _________________________16. PREVIOUSLY UNINHABITED AREAS According to the graph on page 5, it appears that the number of shark attacks are increasing world-wide. However, other factors not necessarily related to the shark attacks themselves may sometimes be responsible for altering data. Name one of the two factors that may have caused an increase in the number of shark attacks reported on the graph without necessarily indicating an increase in the number of actual shark attacks. 7