Steps of The Scientific Method Lab Report
ENVR 1401 Online Scientific Method _________________________________________________________________________________________________________________________ Objectives 1. 2. 3. 4. Students will explain the steps of the scientific method. Students will explain what distinguishes a good scientific hypothesis. Students will define, identify, & give examples of dependent and independent variables. Students will explain the difference between qualitative and quantitative data. _________________________________________________________________________________________________________________________ Please Highlight or type answers in a different color. Information Researchers throughout the world use a standardized technique of answering scientific questions. This technique is called the scientific method. You will use the scientific method throughout this course to critically investigate your environment. There are seven steps to the scientific method: Observation -As you investigate your environment, you will observe many interesting phenomena. Question -You will immediately begin to ask questions about what you observe. Hypothesis -Your question can be turned into a hypothesis which is an educated, yet untested answer to the question. -Your hypothesis must be testable and falsifiable. This means we must be able to design an experiment to test the validity of your hypothesis. If your hypothesis is not true, your results should reject your hypothesis. -What would happen if your hypothesis is not correct? That is your null hypothesis. Experiment -To test your hypothesis, you must design an experiment. An experiment attempts to support or disprove a hypothesis. -One mistake can ruin your results. To ensure your results are correct, be careful when collecting data from your experiment. Results/Analysis -You will need to closely examine data you collect to interpret the results of the experiment. You may have to perform your experiment multiple times to increase your certainty of the results. Conclusion -After analysis of your data, can you support or reject your hypothesis? No results can prove a hypothesis. -If the results of your experiment neither supports nor rejects your hypothesis, you may need to modify your hypothesis. -Explain the data. This is where the lecture material is tied into the laboratory results. Activity 1: Hypothesis After deciding on a question to test, the first thing to do is to propose a possible explanation of the phenomenon or an answer to the question. This is the hypothesis or a statement of change. It is basically an educated guess of what you think will occur during the experiment. In most studies, there is also an alternative null hypothesis (a statement of no change). The null hypothesis is written the same as the hypothesis with the addition of the word “not”. For example the hypothesis “Plants grow taller with fertilizer.” would have a null hypothesis of “Plants do NOT grow taller with fertilizer.” If you were to change any other aspect of the wording it would be considered a completely different hypothesis. It is very important that the hypothesis is scientifically testable and potentially falsifiable. For example, the hypothesis: “Monet is the greatest painter of all time” is not scientifically testable since it is a subjective statement or an opinion. However, the hypothesis could be changed to make it testable, for example: “Monet’s paintings are the most valued based on auction prices.” Exercise 1: Hypotheses • List one example of a falsifiable scientific hypothesis about Oreo cookies. • State the null hypothesis about Oreo cookies. • List one example of a hypothesis about Oreo cookies that cannot be tested scientifically and explain why it cannot be tested scientifically. Activity 2: Variables An experiment is an investigation conducted to test a hypothesis. To do this, scientists design experiments so that alterations to one variable cause another variable to change in a predictable way. A variable is any factor, trait, or condition that can exist as different types or in differing amounts. An experiment usually has three kinds of variables: independent, dependent, and controlled. Designing experiments to test hypotheses requires considerable thought. The variables must be identified, appropriate measures developed, and influences outside of the experimental variables must be controlled. The independent variable will be varied during the experiment, while the dependent variable should change as a result. It “depends” on the independent variable. Controlled variables or constants are also identified and maintained throughout the experiment. If kept constant, the controlled variables should not cause changes in the dependent variable which would confuse the results of the experiment. Many experiments compare the results of the experimental treatments to a control treatment, in which all experimental variables are removed. For example, if different fertilizers were being tested to see their effect on plant growth, the independent variable (the one altered) would be the different type of fertilizers. The dependent variable would be the resulting plant height. To make sure that the fertilizer type was the only factor determining plant growth, everything else would have to be constant or the same for each plant. This would include using the same plant in each pot, the amount of light and water each plant received, the location of the plants, the amount & type of soil used to grow the plants and the list goes on. These are the controlled or constant variables. Finally, to see how the plant grows naturally without any influence one plant would have to be grown without any fertilizer at all. This would be the control treatment that will be used to compare to the experimental treatment (fertilizer types). Exercise 2: List 10 independent variables that can affect seed germination. 1. 6. 2. 7. 3. 8. 4. 9. 5. 10. Activity 3: Experiment The control group in an experiment is the group who does not receive any treatment and is used as a benchmark against which other test results are measured. A control group is used in an experiment as a point of comparison, so that it can be isolated in testing that the experiment did, or did not, have the intended effect. For example, scientists have developed many tests using reagents (substances used to detect another substance) to identify different biomolecules. In order to perform these tests correctly, two different treatments must be completed to provide standards for comparison. The first treatment is called a positive control and contains the variable being tested. The second treatment is the negative control, which does not contain the variable being tested. It is there to make sure your testing chemicals are not contaminated and to see what a negative reaction to the test will look like. • Exercise 3: Identify the parts of the experiment. A researcher wants to find out if spraying fruits with pesticides affects the vitamin levels in those foods. a) the independent variable: _______________________________________________ b) the dependent variable: _________________________________________________ c) two constants: ________________________________________________________ d) the control treatment: ___________________________________________________ Activity 4: Data Data are reported in objective terms that allow for independent interpretation by anyone reading the report. The preferred method of reporting data is the presentation of results in tables and graphs that provide a quick and clear overview of any observed effects. There are two types of data: qualitative and quantitative. Qualitative data include qualities such as color, smell and taste. These are subjectively perceived and can be difficult to express in an objective manner. While everyone conducting the experiment may agree that the solution changed color, there may be variation in what individuals identify as blue, light blue, etc. (I like to think of the “L” in quaLitative standing for “Looks” or “quaLity”.) Quantitative data include qualities that can be measured objectively such as weight, volume, length and temperature. Quantitative data have a number associated with them and can be reported in universally accepted measurable units. This makes it easy for others to interpret the results. (Think of the “N” in quantitative standing for Number.) Both types of data are valid and important. In some instances an experiment may result in just one or the other type of information. Frequently, the investigator may collect and report both types of data. Exercise 4: Label the following as qualitative (L) or quantitative (N). Temperature of 23 °C _____ Measurement of nitrates _____ Increase in color intensity _____ Number of deaths _____ pH values _____ Precipitation _____ Bitter taste _____ Habitat type _____ Sound increase _____ Level of diversity _____ Activity 5: Results/Analysis To understand data better, it is usually shown in some type of graphical format. The same data can be portrayed in different formats depending upon what is being emphasized. A pie chart shows the proportions of different categories (qualitative data). The amount of the pie (circle) correlates to the percentage. It can be as simple as just two categories or it can contain several categories. The more categories a chart has, the more difficult it is to read. If there are many categories that have small numbers they are frequently lumped into an “Other” category. A bar chart is used to show comparisons between data. The independent variable is found on the x-axis while the dependent variable is put on the y-axis. Finally, the line graph is used to show data changes over time. Once the points are plotted a best fit or trend line is drawn to show a smooth representation of the data. It is not necessary to connect each dot. The axis labeling is the same as it is for bar charts. Graph showing a best fit line. Exercise 5a: Creating a complex pie chart. Create a pie chart for a characteristic with at least four categories but not more than six. Choose a characteristic that varies among students. Appropriate examples include shoe type, favorite subject, mobile phone service, or type of car owned. Poll friends and family to gather data and create a pie chart with your data. Graph Title: _______________________ Category Number of Students Percent of Students What information can be inferred (deduced) from the graphs you created? Can you predict what the graphs would look like if you had polled 100 people? Be specific in your explanations- this answer should be 6 thoughtful sentences long. Exercise 5b: Creating a bar chart. The information in a pie chart can also be shown as a bar chart. The y- axis on the bar chart can be percentages or any quantitative variable. Bar charts must always have both axes labeled and a figure description given. Create a bar chart for the data you collected in exercise 5a. (Feel free to delete given graph paper & insert personally created graph.) What information can be inferred (deduced) from the graphs you created? Can you predict what the graphs would look like if you had polled 100 people? Be specific in your explanations- this answer should be 6 thoughtful sentences long.
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