Environment Lab questions

Exercise 1: The Scientific Method: Hypothesis Development & Testing

Materials:

•    Laptop computer
•    Milk
•    Vinegar
•    Beaker
•    Stir rod
•    Cookie Cutter
•    Food Coloring
•    Strainer/Sieve
•    Candy Bar
•    Straw/knife
•    Coin

Background:
Scientists explore issues in the world around us using the scientific method (Figure 1).

The process of using the scientific method begins by first making observations.  Observations lead to the identification of a problem of interest.  After a problem is identified, a question (or even multiple questions) and potential answer(s) for that question, known as a hypothesis, are formed.  Hypotheses are often referred to as “educated guesses”; however, a hypothesis should not be a wild guess, but rather a series of questions that result directly from your observations.  Through extensive research and experimentation, scientists attempt to prove their hypotheses are either correct or not correct.  Often, scientists must repeat research, experiments, and even hypothesis development until the question posed can be adequately answered.  This process can be long and frustrating, with some scientists working on one question their entire professional career.

After experimentation is completed, scientists carefully consider their results.  Scientists question the outcome of the experiments, whether the results support the hypothesis, and why the results may or may not support the hypothesis.  Results are then published for others to read commonly in peer reviewed publications, which means that the hypotheses, data, and results have been carefully reviewed by other scientists within the same specialties to ensure the quality of the data and the results are valid.  Scientists may use this data as background research for other questions or even to attempt to repeat the original experiment.
Another important aspect of science involves the repeatability of results and the quality of the data.  In order for results of experiments to be accepted by other scientists, the results must have the potential to be repeated.  The more repetition of results, the higher the level of confidence placed on the results. Ultimately, if a hypothesis is strongly supported by the scientific community based on compelling results, the hypothesis may eventually become a scientific Theory (i.e. evolution, the Big Bang, plate tectonics, etc.).

In this lab, we will complete three different exercises to better understand the scientific method.  The first experiment involves a coin, the second a candy bar, and the third involves the use a chemical reaction between borax, glue, and water.  Throughout the exercises, you develop hypotheses, make observations, and collect data.   You will also evaluate and re-evaluate your original hypotheses.

Activity 1:
This activity will require that you use a regular two-sided coin.

Activity 1 Questions:
1.    If you flip the coin, what do you think will be the outcome (i.e. heads or tails)?

2.    If you flip the coin 10 times what percentage of the time do you think the coin will land heads up?

3.    Flip the coin once – what happened?

4.    Flip the coin 10 times – what happened

5.    Develop a hypothesis based on these results for flipping the coin 50 times.

6.    Create a table to record your results on another piece of paper, and then flip your coin 50 times.On another piece of paper or using a graphing program, such as Microsoft Excel, create a graph of your results.

7.    How did your actual results compare with your hypothesis?

8.    Does your hypothesis need to be revised?  Why or why not?
Activity 2:
Geologists use several principles of relative dating to understand the relationships between different layers and features in rock units (Figure 2).  Those principles are:
•    Uniformitarianism – the idea that processes operating today also operated in the same way in the past, although the rates may have been different.  Because of this relationship, by understanding modern processes, we can use what we have learned to evaluate the past.

•    Principle of Original Horizontality – layers of sediments were originally deposited in a horizontal fashion.  Generally, rock layers that are flat have not been disturbed.

•    Principle of Superposition – in an undeformed sequence of sedimentary rocks, the oldest rocks are on the bottom.

•    Principle of Cross-Cutting Relationships – younger features cut across older features.

Using these principles of relative dating, you will examine a candy bar.  Each person in your group should obtain a candy bar.  You should try to have a variety of candy bars at your table.

Activity 2 Questions:

1.    Place the layers and features from Figure 2 in order of oldest to youngest.

2.    Based on what you know about your candy bar, draw what you expect a cross section of the candy bar to look like.  In other words, what do you think the layers of the candy bar would look like if you were to slice it in half?

3.    Using your sketch, come up with a sampling strategy to “core” your candy bar with a straw to verify your hypothesis regarding the candy bar layers.  Do you need just one core, two, three?  How many cores are necessary to verify what the internal structure of the candy bar looks like?

4.    Either core your candy bar or make several slices.  On another piece of paper, sketch a diagram that illustrates where your samples came from and describe what you see.

5.    Using the principles of relative dating and your sample sketches, describe the relationships between the layers and features in each of your drawings.

6.    How closely did the actual layers match your initial drawing of the layers?
7.
Activity 3:
You have been given several materials and are unsure of what will happen when these substances are combined.  These substances are:

•    250 mL of milk
•    60 mL of vinegar
•    Food Coloring
•    Strainer/Sieve
•    Cookie Cutter/Mold

Before doing anything with these materials, answer questions 1 and 2.

Activity 3 Questions:
1.    Make 4 observations about the materials before they are combined.
2.    Form a hypothesis regarding what will occur when the materials are combined.

Heat the milk and food coloring in a 400 mL beaker on a hot plate until hot but not boiling.  Add the vinegar and stir.  Pour the mixture through the strainer at the sink.  Rinse with water at the sink and collect the materials on the strainer.  Once cool enough, shape the materials and form into a mold.

3.    What actually occurs when the materials are combined?  Was your hypothesis correct?

4.    Describe the new material you created?  Were the results surprising?

5.    Now do some of your own experiments using the resulting substance.  Come up with 2 questions, hypotheses, and results.

a.    Question 1:

Hypothesis 1:

Result:

b.    Question 2:

Hypothesis 2:

Result:

6.    Was this a good method for creating your product?  How is this product prepared commercially?

7.    Scientists have been able to identify and explain many aspects of our world by using the scientific method.  Name 3 important scientists and their contribution to environmentalscience.