As we have learned in science class, most of our transportation is powered by fossil fuels.  When fossil fuels are burned, harmful greenhouse gases and pollutants are placed in the air.  Fossil fuels are considered to be non-renewable sources of energy, because they come from the remains of living things more than 300 million years ago that can in no way be replenished at the rate at which we humans are using them!  Therefore, we designed experiments to determine how best to propel rockets using Alka-Seltzer + water as a model of an alternative and renewable source of energy.

Before designing our experiments, we made some observations of other chemical reactions to get a better sense of how to design our own experiments.

As with every controlled investigation, we only change one variable in order to observe the effect(s) of that one change. Think back: What was the ONE variable that your group decided to change to the Alka Seltzer + water chemical reaction?  What is another way to describe the ONE variable that a scientist changes in an experiment?  What is another way to describe what the scientist measures?

Each group only changed one variable in order to see the effect(s) of that one change.  Some groups changed the temperature of the water or the amount of water, while other groups changed the size of the Alka-Seltzer tablet.  The group above changed the temperature of the water, and predicted that the hotter water would dissolve the tablet faster.

As a scientific community, we shared our group's results. Through our first round of experimentation, we learned that increasing the temperature, increasing the amount/volume of water, and crushing the Alka-Seltzer tablet all decreased the amount of time it took for the Alka-Seltzer to dissolve (for the chemical reaction to occur).

Before designing our rockets, we took a break and visited the animals!  What was your favorite animal at the Environmental Study Center?

After experimenting to better understand how the size of Alka-Seltzer, temperature and volume/amount of water affect the speed of the chemical reaction, each group picked one variable (= independent variable) to change to their Alka-Seltzer powered rocket to get the rocket that can propel the highest.  Most groups changed the temperature or size of the Alka Seltzer.  Do you remember which group had the highest rocket propulsion?  Do you remember this group's independent variable?

Last but most certainly not least, we learned that there is no such thing as failure in science.  There is also no such thing as an "incorrect" hypothesis, because the whole point of testing a hypothesis is to learn something new (and learning something new is never wrong/right/correct/incorrect).  Instead, we say that our hypothesis was "not supported" and reflect on the process and possible limitations that occurred in the planning/design and execution of the experiment, and also evaluate and possibly re-think our original hypothesis!

Scientific Method = Gathering Evidence

Last week, we learned that the Scientific Method is an organized method used by scientists to find and gather evidence (data) to support a claim (argument) about what the scientist observes.  There are many versions of the scientific method, but all versions of the scientific method involve trying to answer a specific question, and experimenting to find the answer.

The version of the scientific method that we will use in my class was given to me by my dear friend, Dr. OPHERC:

• Observation: The observation is simply any information gathered using the senses or an instrument.  A scientific investigation begins with an interesting observation in the world that generates questions that can be tested.

• Problem/Question: The problem/question is the specific question the scientist will attempt to answer through experimentation.

• Hypothesis: The hypothesis is the claim of the scientist, or an educated guess about the answer to the problem/question.  A hypothesis is based on sufficient observations, prior knowledge, and background research.  

• Experiment: The experiment is when the scientist actually tests his/her hypothesis for supporting evidence using detailed procedures, appropriate materials, and scientific measuring tools.  During the experiment, the scientist records all of his/her qualitative and quantitative observations.

• Results: The results are all of evidence (the qualitative and quantitative observations) gathered throughout the experiment.  The results are often displayed in tables, charts, and graphs for further studying. 

• Conclusion: The conclusion is the reasoning of the scientist that explains the meaning or significance of the results.  In the conclusion, the scientist links the evidence from the experiment back to the original claim (hypothesis).     

Scientific Explanation = Goal of a Scientist

During the first week of school, we learned that science is a way to develop explanations for what we observe, using the evidence we gather through our own experiments, and through the experiments of other scientists.  A scientific explanation, so to speak, is the scientific way of explaining what we observe in the world (and outside of the world, too!).  A scientific explanation is essentially a claim (about what a scientist observes/observed phenomena) that is supported with evidence and reasoning.  
The goal of a scientist is to develop scientific explanations to share with the scientific community, and the purpose scientific method is to gather the "evidence" component of the scientific explanation.  

But what is a claim?  What is evidence?  And what is reasoning?!  These components of a scientific explanation (C.E.R.) have been outlined below.

C.E.R. = Parts of a Scientific Explanation

• Claim: a conclusion that attempts to answer/address a testable scientific question. 
• Evidence: appropriate and sufficient data from an experiment, other scientists' experiments, reading material, and/or other observations that support the claim.  
• Reasoning: a justification that links the claim and evidence that incorporates appropriate and sufficient scientific principles; requires background research.  

Connecting the Scientific Method with C.E.R.

Last week, we performed an experiment to gather evidence in order to develop a scientific explanation. The question we addressed was, "What is the most common color in a 2.17 oz Original Fruit bag of Skittles?"

Below is an outline of how we gathered our evidence via the Dr. OPHERC.  We will use class 711's data for our example.

1.  The scientific method began with an observation.

Observation: There are five different colors in a bag of skittles - red, yellow, orange, green, purple.  Every time I eat a bag of skittles, the frequency (how many) of each color seems to be different.  

2.  This observation inspired, or led to, a question for investigation.

Problem/Question: What is the most common color in a 2.17 oz "Original Fruit" bag of Skittles?  

3.  We made a tentative claim (hypothesis) to test, based on our observations, background research, and prior knowledge.

Hypothesis: If purple is the most popular color of Skittles, then it will be the most common color in a 2.17 oz bag because the makers of Skittles will likely accommodate the preference of the consumers.  Furthermore, according to Skittles.com, green should make up 19.7% of a 2.17 oz bag, yellow should make up 19.5% of a 2.17 oz bag, orange should make up 20.2% of a 2.17 oz bag, red should make up 20% of a 2.17 oz bag, and purple should make up 20.6% of a 2.17 oz bag. 

4.  We then tested our hypothesis through an experiment to gather evidence.

Experimental Procedure:
1.  Open the bag of Skittles onto your sheet of paper towel.
2.  Group your Skittles according to color. 
3.  Count how many of each color are present in your group’s bag and record this info in table 1.   
4.  Analyze your data by creating a bar graph on Table 2.
5.  Make sure to label the graph showing colors and numbers of Skittles. 
6.  Form a conclusion.  State whether your hypothesis was correct or incorrect and why. 

5.  Next, we graphed all of our data (evidence).

Results:
Average number of red (class 711): 11.5 pieces
Average number of yellow (class 711): 13.3 pieces
Average number of orange (class 711): 10.2 pieces
Average number of green (class  711): 13.5 pieces
Average number of purple (class 711): 10.2 pieces

6.  We then made a conclusion by determining whether or not the evidence gathered supported our original claim.  The conclusion is essentially our reasoning.  The conclusion addresses our original claim (was it correct?  incorrect?), provides our evidence, and links our evidence back to our original claim.

Conclusion: My hypothesis was not supported through this experiment because I predicted that purple would be the most common color, and my results show that green is the most common color in this experiment.  The average total number of candies in class 711 was 58.6 pieces.  There was an average of 10.2 red candies, 13.3 yellow candies, 10.2 orange candies, 13.5 green candies, and 10.2 purple candies in a 2.17 oz bag.  Class 711's results were different from class 711, 714, 715, and 716. My next step is to average the data from all four classes.  Since every class has a different average frequency of colors, the results do not provide enough evidence to support or oppose my claim that purple is the most common color of skittles in a 2.17 oz bag.  Furthermore, since Skittles.com states that green should make up 19.7% of a 2.17 oz bag, yellow should make up 19.5% of a 2.17 oz bag, orange should make up 20.2% of a 2.17 oz bag, red should make up 20% of a 2.17 oz bag, and purple should make up 20.6% of a 2.17 oz bag, it is important that we increase our sample size in order to have a fair test.

Homework:

Answer the following questions in your science notebook.  Write the questions AND answer in complete sentences.

1.  Why do scientists use the scientific method?
2.  What is a scientific explanation according to this article?  Cite your evidence.
3.  How is the "reasoning" in a scientific explanation related to the claim and evidence?  Explain.
4.  According to this blog post, a claim is a conclusion that attempts to answer/address a testable scientific question.  What is another way to define claim?
5.  According to this blog post, evidence is appropriate and sufficient data from an experiment, other scientists' experiments, reading material, and/or other observations that support the claim.  What is another way to define evidence?
6.  Were we able to gather enough evidence through our Skittles experiment to support a claim that a particular color is the most common in a 2.17 oz bag of "Original Fruit" Skittles? Explain.
7.  Using the scientific method does not always provide the necessary evidence to support the claim (hypothesis) of the scientist.  What do you think a scientist should do in the case that the evidence does not support the claim (hypothesis)?  Explain what you think should be the next steps for the scientist.

Due: Monday, October 21, 2013.