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Instructions:
Please answer the questions interspersed below, found under the Activities headings, in a Word document. If you need to add pictures, graphs, etc., go ahead and add them directly into the Word document that you upload. Your answers need to be in your own words.
Objectives:
Apply the scientific method to understand the world around you.
Formulate a testable hypothesis from the information gathered.
Design and perform an experiment to test predictions.
Interpret and apply data.
Create graphical representations of data.
Use the results of your experiment to draw conclusions.
Introduction
Science begins with observations and curiosity. We use science as a process to attempt to understand how the world around us works by asking questions and collecting evidence to answer our questions. The scientific method is the common steps or procedures scientists use to investigate the world. We will learn the steps of the scientific method to help you think like a scientist!
Observe & Question The first step of the scientific method is observation. Interesting or curious observations lead scientists to question the phenomenon or ask what could explain the phenomenon. Hypothesis The second step of the scientific method is to formulate a hypothesis to explain your observations. A hypothesis is an educated, testable guess to answer your above question. Experiment The third step of the scientific method is to form an experiment to test your hypothesis. An experiment is a carefully designed, controlled, and repeatable manipulation of the world to test your hypothesis. The results of the experiment are recorded as data and presented in an appropriate format. Conclusion The final step of the scientific method is to draw conclusions. Based on the results you obtained, the data may support or reject your hypothesis. If necessary, you may change your experiment as you make new observations, develop a new hypothesis, and then redo the whole process. We will use the following observation to illustrate the scientific method:
A scientist observes that a new diet given to his rats appears to cause emaciation (extreme weight loss) and that it is lacking a specific chemical, Y. This leads to the question: “Is Chemical Y an essential component of the rat diet?”
Activity 1: Hypothesize
The scientific process begins when something observed draws interest. Your interest leads you to apply the scientific method to help understand what, why, or how something occurs in the world. In this activity, you will evaluate a few hypothesis statements. Remember that a good hypothesis:
uses clear, well-defined language
can be tested experimentally
An example of a hypothesis for the above scenario would be:
Taking away Chemical Y from the rat diet will lead to weight loss in the rats.
Note: A good hypothesis does not necessarily have to be correct. Answer the following questions:
Activity 1
Use your knowledge of a hypothesis to determine if the following are good hypothesis statements. If not, suggest how they could be changed to be good hypothesis statements.
Chocolate causes acne.
Bark beetles kill trees in the spruce family.
Doritos are better than Lays potato chips. Bacterial growth can be reduced using pesticides.
The sun will rise tomorrow.
In 100 years, people will fly.
Activity 2: Experimentation
Experiments are used to test a hypothesis. They are designed to consider all components, not just the variable being tested. A good experimental design will account for:
Independent variable: the variable that is manipulated in the experiment, or what changes
Dependent variable: the variable that is measured to determine the effect of the independent variable, or what’s measured
Standardized variables: the variables that are intentionally maintained in the experiment, or what’s constant
At least two groups will be analyzed in an experiment: one control group and one experimental group.
Experimental group: the group to receive the treatment or independent variable change
Control group: the group that will not receive the treatment or independent variable change, used to set a baseline or as a group to compare results to
To test our above rat hypothesis, a scientist could split same sex rats into two groups: one that will receive chemical Y in their diet and one that will not receive chemical Y in their diet. The rats must have standardized conditions of treatment, including the same amount of food given at the same times, the same watering amount and schedule, and kept at the same temperature in a similar enclosure. The only difference observed in the two groups should be the presence or absence of chemical Y in their diet. Answer the following questions:
Activity 2
Given the following scenario: You know that caffeine is a stimulant, and you are curious about the effect that it has on heart rate. You design an experiment to test the effects of caffeine on the heart rate of Daphnia. You obtain 240 Daphnia and divide them into 6 groups, two beakers for each treatment, that will receive: 0%, 1%, 2%, 3%, 4%, and 5% caffeine water solution. Answer the questions below.
Write a hypothesis for the experiment.
Identify the independent variable, … the dependent variable.
What are some variables you would want to remain the same during the experiment?
Identify the control group. Why is a control group important?
Why would you use two beakers for each treatment, or what is the purpose of the repetition?
Activity 3: Data Analysis
Through the course of an experiment, you collect data or results that will need to be presented appropriately and in a way that is easy to interpret. This is done using a mixture of tables, graphs, and other visual aids. Our data from the example experiment could be represented in a table:
Table 1.1 Data from experiment on rats. Weights are represented for rats with Chemical Y in their diet, and those that are Chemical Y deficient.
Chemical Y Added Chemical 7 Deficient
Rat 1:
300 g
Rat 1:
170 g
Rat 2:
302 g
Rat 2:
201 g
Rat 3:
290 g
Rat 3:
163 g
Rat 4:
317 g
Rat 4:
204 g
Rat 5:
405 g
Rat 5:
152 g
Rat 6:
275 g
Rat 6:
215 g
Rat 7:
303 g
Rat 7:
123 g
Rat 8:
392 g
Rat 8:
177 g
Rat 9:
299 g
Rat 9:
219 g
Rat 10:
337 g
Rat 10:
107 g
Since duplicate treatments were performed, we could calculate the average, or mean, rat mass by adding together each treatment and dividing by the total number of treatments.
That would look as follows:
Table 1.2 Data on the average weight of rats.
Chemical Y Added Chemical Y Deficient
Average Rat Mass (g) 322.0 g 173.1 g Now, we can present this data graphically using either line graphs or bar graphs. The type of graph you use depends on the type of data you have gathered. If the data is continuous, meaning there are an infinite number of values for your independent variable, then a line graph would be the appropriate choice. If the data is discrete, meaning there are a limited number of values for your independent variable, then a bar graph would be the appropriate choice. When we represent our data graphically, usually, the independent variable is placed on the X-axis (horizontal) of the graph, and the dependent variable is placed on the Y-axis (vertical) of the graph. The range of values represented on both axis should be only slightly larger than the range of values found in your data. It is essential to include clearly labeled units and for the scale intervals to be the same. Also, it is important to give your graph a title, so viewers know what you are representing. For our rat data example, it would make more sense to use a bar graph. There are only two independent variable possibilities, Chemical Y added or Chemical Y Deficient, which makes it a discrete variable. A graph of the data could be constructed with the presence or absence of Chemical Y on the X-axis and rat mass on the Y-axis. Activity 3
Using the scenario from Activity 2:
Place the below data in a table. There are two trials in each treatment group, with heartbeats per 20 seconds recorded. Include columns in your table for the average number of heartbeats per the 20 second interval for each treatment, and include the average heart rate or beats per minute for each treatment. (Your table should have 5 columns and 7 rows.)
Group 1 (0%): 60 beats, 57 beats
Group 2 (1%): 66 beats, 69 beats
Group 3 (2%): 74 beats, 78 beats
Group 4 (3%): 84 beats, 85 beats
Group 5 (4%): 90 beats, 92 beats
Group 6 (5%): 101 beats, 103 beats
Make a graph of the average heart rate vs. the treatment group. Be sure to include clearly labeled axes with units, a title, and a proper range of values for your data. Would it be more appropriate to choose a bar graph or a line graph to represent this data? Why?
Based on this data, what conclusions can you draw about whether you support or reject your hypothesis from Activity 2. What additional information might you want to gather to help determine the effects of caffeine on heart rate?
Activity 4: Designing an Experiment
For the final activity in this lab, you will be designing and executing your own experiment, applying everything you have learned thus far. To begin, you will need to generate a research question. Make sure your question is something that you can easily execute in a minimal time frame. For example, does distance have an effect on the accuracy of shooting a paper ball into a trash can, or does salt have an effect on the boiling temperature of the water?
Then, you will develop a hypothesis based on your question. Remember, a hypothesis should be clear, well-defined, and able to be tested. From your hypothesis, you will then generate a research plan that you will execute. Be sure to outline:
Independent variables
Dependent variables
Standardized variables
an Experimental group
a Control group
Procedures you will use to test your hypothesis
After you come up with an experimental plan, you will run the experiment. Be sure to gather appropriate data and organize it into a table and graph. Lastly, you will conclude whether the data you gathered supports or does not support your hypothesis. Following our example experiment, the effects of Chemical Y in the diet of rats on their weight, we can conclude that our data support our hypothesis. We had a fairly large difference between the two treatment groups that supports our claim that an absence of Chemical Y leads to weight loss in rats. Answer the following questions:
Activity 4
You will be including a write up here for your mini-experiment that you ran. One of the example questions may be used, the distance and paper balls or salt and boiling water. We will put this in the format of a scientific research paper. You will have an introduction section where you include the research question, variables, experimental groups, and your hypothesis. It may be in a list format, as we are just learning the basics of the scientific process. Next, you will have a methods section that will list your procedures performed during the experiment. The following will be the results section that contains the table and graph of your data. Then, finally, you will have a discussion section that includes your conclusions based on your hypothesis.