Heat Transfer

I set up this experiment by using only three insulators instead of the four that we were told to use.  I did this because of a lack of supplies, primarily beakers, and because of the need for a control in this experiment.  I used cheesecloth, a hand towel, and aluminum foil for my insulators.  The water that I used had an initial temperature of 25°C, meaning that this is the temperature that the water could possibly cool down to after being heated, if given enough time to do so.  I heated the water to 72°C and put 200mL of water into four separate beakers (instead of mugs).  I put each insulator tightly on separate beakers, put a rubber band around it, and waited 30 minutes.  After 30 minutes, the control beaker’s temperature cooled to 39°C, the cheesecloth to 41°C, the hand cloth to 47°C, and the foil to 51°C.  Based on just this information alone, I could adequately conclude that the aluminum foil served as the best insulator. 

Additionally, however, I noticed that the beaker that had the foil over it also produced the most condensation.  Condensation decreased as the difference between initial and end temperatures increased.  This was due to the following reasons, as the water cooled, thus meaning that heat energy was released, condensation occurred.  But, as this cooling process continued, condensation exceeded the rate of evaporation, thus reverting water molecules that were in the gaseous states as a result of the hot water releasing steam back to the liquid state.  Because there is little room for these molecules to move, the water molecules, in the liquid state, stick to the sides of the beaker.  Therefore, the efficiency of each insulator was shown through the end temperature and the degree of condensation. 

All in all, this experiment was a simple demonstration of conduction and an easy way to test the efficiency of a variety of insulators.  Conduction occurs when heat energy is transferred from a warm area to a cooler area, from molecule to molecule.  In this experiment, heat energy was simply transferred from the water in the beaker to the outside environment.  The water was warmer than the outside environment temperature, and therefore “escaped” from the water into the air. 

It makes sense to me, and I could be wrong, to say that the reason that the foil was the best insulator is due to the fact that it is the most solid insulator.  In other words, the foil’s structural molecules are the closest together, thus trapping the heat energy, and any gaseous water in the beaker at the greatest rate. 

Although I did not test this, I would hypothesize that these insulators would work the same, or relatively similarly on alternative substances.  In other words, foil would keep heat energy in these materials most efficiently, just like it did for water.  The overall ability of these materials to retain heat, however, is a much more difficult question, as it brings in the concepts of heat capacity and the first law of thermodynamics.  A substance with a higher specific takes longer to heat up because more energy is required in order to raise its temperature 1°.  Due to this fact, a substance with a higher specific heat heats up slowly, holds a greater amount of energy, and cools down slowly.  Therefore, if we were to test the efficiency of insulators on alternative substances, such as spaghetti or a hot dog, those substances with higher a specific heat will naturally take longer to cool down.  

Engaging in Guided Inquiry with Marbles!

During this guided inquiry experience, I chose to discover answers to the following question: How do different surfaces affect the momentum of marbles?  Initially, my head started spinning with possibilities regarding this question.  Although I did not test this, I even played around with the idea of testing on hot and cold surfaces.  Instead, I took the generic route, due to a time crunch in the past few days, and tested two marbles, varying in mass and size, on four household surfaces; carpet, a bed comforter, a smooth hardwood floor, and a tiled kitchen floor.  As I brainstorm ideas for this experiment and started going through the different variables that would be relevant, I soon discovered that I would need to have a very specific set of parameters for each test.  For example, when I tested each marble, it was rolled, with no exerted force from me, down a folder that was propped up against a 1.5-inch book.  To ensure that the folder was placed at the exact same spot for each test, thus ensuring the same exact slope each time, I marked the sides of folder at 9.5 inches, designating where to place it on the book.  Additionally, I used this same mark as my placement from which to begin rolling the marbles.  I rolled each marble individually, and started with the front of the marble placed on the line on the folder.  Lastly, I placed a yardstick at the base of the folder (where it meets the floor).  I measured all tests in centimeters and kept record of how far the marbles rolled according to the rear of the marble.  I performed trials for each marble on each surface three times, then calculated an average for each.  I recorded this data in an Excel chart (found below, modified for formatting reasons). 

After compiling my data and performing each trial, I came to the following conclusion.  When these two marbles, varying in size and overall mass, are rolled from a constant position on the folder, thus allowing for acceleration to build up from a consistent distance, the marble with the greater mass will travel a greater distance on any of the surfaces tested.  This is primarily due to its higher mass, which causes it to gain more velocity while it is traveling down the slope of the folder, thus gaining more momentum when it hits the base of the folder.  This momentum is then carried off the slope onto whichever surface and is transferred to distance. 

In addition, after this experiment was complete, I found a few variables that were not efficiently controlled in this experiment that could very well have affected my results.  For example, the marble almost never traveled in a straight line.  Also, the marble did not always leave the folder at the same spot, thus causing it to travel a different path on the tested surfaces.  Both of these variances could have easily affected my results.  Now, I would not conclude that these variances would have affected my overall conclusions, however.  Regardless, if I were to perform this experiment again, I would modify by setup in order to account for these obstacles. 

In the classroom, students would highly benefit from an experiment on momentum like this.  The guided inquiry process, which only supplies students with a question to study, truly allows students to take control of their learning and make their own discoveries in science.  When this is achieved, the retention of knowledge is much more likely.  If this were a classroom activity, I might make the question more open to the use of a variety of materials.  For instance, rewording it to state, “How is momentum affected by different surfaces?”  This gives students the opportunity to still design an experiment, but does not hold them to using only marbles.  Additionally, if marbles were used, I would have students calculate the mass of each marble and analyze how the specific mass affects momentum (as observed through distance traveled).  Is there a ratio in play here?  To further analyze this question, a more varying range of marbles could be provided as well. 

Data: (in centimeters to the nearest half)

Blue Marble (on carpet)

1: 48.5

2: 43

3: 48.5

Average: 46.7

Green Marble (on carpet)

1: 61.5

2: 58.5

3: 56

Average: 58.7

Blue Marble (on comforter)

1: 10.5

2: 16

3: 16

Average: 14.2

Green Marble (on comforter)

1: 16.5

2: 17.5

3: 15

Average: 16.3

Blue Marble (on smooth floor)

1: 224.5

2: 232

3: 224

Average: 226.8

Green Marble (on smooth floor)

1: 270.5

2: 283

3: 278.5

Average: 277.3

Blue Marble (on tiled floor)

1: 169

2: 184

3: 172

Average: 175

Green Marble (on tiled floor)

1: 202

2: 215

3: 217.5

Average: 211.5

Thoughts on a Structured Inquiry Lesson

As I wrote in this week’s application paper, in reflecting on this structured inquiry lesson, I found that my students worked incredibly well in their small groups.  I tried something sort of differently with this lesson with regard to grouping.  Instead of completely directing the flow of the class, as I might have normally done with a lesson such as this, I designated leaders in each small group of 3-4 students to progress the group through a variety of tasks including brainstorming, analyzing data, constructing graphs, and answering critical thinking questions.  I saw true growth in my students through this exercise.  Not only was I impressed by the group leaders, but also by the attentiveness and respect displayed by other students. 

Many of these students brought relevant background knowledge into the lesson as well, which allowed them to relate our study of predator-prey relationships and natural selection to the natural world.  This lesson was aimed at interpreting how environmental influences might impact relationships in nature, and how these same influences may be positively or negatively impacting the process of natural selection, at an observable level.  This lesson served as a study that can be used for comparison reasons throughout the next few weeks as the topic of evolution is explored more deeply.  More specifically, my students walked away with knowledge of specific environmental influences that affect species in nature and how humans are both helping and hurting this impact.  We will further analyze how and if these influences are relevant to natural selection at a more large-scale and long-term level (i.e. extinction, genetic variation, long-term species adaptation). 

As my students progressed through this case study, of both moose & wolves and humans & the Earth, I could see the connections that they were making to how humans are largely adversely affecting the Earth, bringing up such topics as overpopulation, pollution, and global warming.  We were able to discuss, at the end of class, the implications that some of these influences might have on the Earth in the next 10, 50, 100, 1,000 years.  I think some of my students’ eyes were opened to how we seem to be pushing along the process of evolution, from a natural selection perspective, thus making it not entirely natural, as it was intended to be.

Melting Icebergs!

Melting Icebergs Experiment:

Question 9: Extended Questions

a. What happens if the polar ice caps melt?

Our polar ice caps comprise approximately 75% of Earth’s fresh water.  This being said, if the polar ice caps melted, it would have quite dramatic effects on the planet.  Most of our metropolitan areas are located along continental coasts.  Based on the experiment, as the polar ice caps melt, ocean levels will rise, subsequently flooding our shores first.  Although I do believe that global warming is a true concern for our planet and highly based on anthropogenic causes, I am unsure how relevant the melting of polar ice caps is to the general public when discussing possible implications of global warming.  Let’s think about it for a second.  Most of the world’s ice is in Antarctica.  With average temperatures around -37°C, the melting of this ice mass is unlikely.  But, even if a portion of the Earth’s polar ice caps melted, either in the Northern or Southern Hemispheres, this would still cause ocean water levels to rise a few feet.  These few feet could still be catastrophic, especially to these highly populated coastal metropolitan areas.  As these levels continue to rise, the addition of salt water to farmland could also be destructive to crop production.

b. What other questions do you have about this Science Inquiry Experience?

-       What is the current rate of polar ice cap melting?

-       How much does the Earth’s climate/average temperature increase each year?

-       How do carbon emissions increase each year?

-       Since the “green movement” that began a few years ago, including “green” appliances, vehicles, and other machinery, has the rate of global warming and/or carbon emissions decreased at all? How much more of this will it take to either stop global warming where it is or reverse its effects?

STEM Lesson Design Reflection

This past week’s lesson design assignment was not particularly challenging at first because I had many lessons already made to choose from, but once I figured out that we had to specifically relate it to a “historical background” benchmark and a unifying theme of science I had a much more difficult time coming up with a specific lesson to construct.  I guess I found this difficult because of the degree to which these standards were history/social studies based.  Once I found that a lesson on natural selection would be applicable, this assignment was simpler.  So, in sum, my feelings towards this assignment flip-flopped quite a bit!

On another note, however, I was very pleased to see that we were asked to construct a lesson using the 5 E’s format.  This is how I construct all of my lessons, as I was taught this method of lesson planning during my undergraduate education and teacher training.  It is so conducive to the administration and facilitation of inquiry-based and cooperative learning lessons.  The particular lesson that I constructed was a combination of two lessons that I currently teach, modified and condensed to fit an hour-long class period.  This was a great experience because it made me realize how these two lessons could easier be condensed and made more effective because of it.  I am interested to see how this new lesson will work in a real classroom setting.  I tend to be highly reflective during the lesson planning process, and have always had a knack for time management in the classroom.  For these reasons, I think that I produced a really solid lesson.  I cannot wait to implement it within the next two months!

To begin...

As this school year begins, I am extremely pumped to be such a great journey with my students!  Just as last year intrigued me because it was my first year teaching, so does this year, but for so many more reasons.  I strongly hope that I can apply knowledge and practices gained in this course directly to my classroom!