Insulative Properties Experiment

Insulation of Covers and Heat Loss

This week I worked on an experiment involving boiling water, a set of identical ceramic cups, and different materials to use as a lid.  The idea of the experiment was to predict what type of cover would better insulate the liquid in the cup, using temperature measurement as a result.  The assumption would be that the better insulator we had the better heat would be retained in the liquid.  Heat transfer can happen in one of three ways, conduction, convection, and radiation (Tillery, Enger, & Ross, 2008).  I believe that the major way that cooling will occur in this test will be through conduction.  This is where energy is transferred from molecule to molecule (Tillery et al., 2008).  I believe that the ceramic cup will block most of the heat radiation as well as the effects of convection that will occur in the test. 

One of my hypotheses is that most of the heat will be lost to the atmosphere through the top of the cup where the conduction of the heat will flow from water, to the air in the cup, to the lid, to the atmosphere.  Given this as a starting point for the experiment, I will then postulate that if heat is going to transfer through conduction.  The better insulator the lid is, the slower the energy will dissipate to the atmosphere.  I selected a few different types of materials for this; a book, plastic bag, ceramic plate, and aluminum foil.  With this I added a control with no cover.  Looking at my hypothesis I will predict that after one hour the water will be hottest in the cup with the ceramic, then the book, the plastic, the aluminum, and finally the control.  I believe that this will be the case because of the mass of the objects in the book and ceramic.  Mass is an integral part of the calculation of specific heat (Tillery et al., 2008) and the higher the mass the more resistant it is to temperature change.  The aluminum is a little different case, I know that the other materials I chose are of mostly organic origin and do not contain a conduction band.  The aluminum (being a metal) has a conduction band so it follows that it is a poor insulator while the plastic should be better.

In the appendix I have recorded my results.  The results of each of the materials were very similar, with there only being one degree separation between the different lid types.  I was a little surprised by my results so I ran the test again and achieved similar results.  It is interesting that these results go against what I saw as something that I knew the results of before I ran the test.  I am reminded that this is what students must feel like every time we have them make a prediction on an experiment before they really know what is going to happen, it can be a little embarrassing to be wrong.  This strengthens my belief that it is essential for teachers to establish an environment that is safe and comfortable to students (Laureate Education, 2010).  I believe that the test could be better improved by further insulating the ceramic cups to eliminate heat loss through the sides.  It would also be a better test of insulative properties if we were able to have cups constructed of the same material as the lids. 

I can explain my results in several ways, the first being that the cups that I used were not completely filled with water and there was a large air gap between the cup lid and the water surface.  This would override the insulative properties of the lid since air is a great insulator.  This is demonstrated with the aluminum cover where it is well established that aluminum is not a great insulator but did well in this test as a cover.  I believe that this test will show that any cover would perform similarly.  Before I assigned this as a laboratory in my classroom I would need to perform this test a few more times to ensure that I understand why I achieved the results I did.  I would also modify the test to achieve more differentiation between the insulators.  An example of this would be to change the material the cup is made of to be the same as the cover.  

References

Laureate Education, Inc. (Producer). (2010). Virtual Field Experience™: Managing the Differentiated Classroom [Video webcast]. In Teacher as professional. Retrieved from http://www.courseurl.com

Tillery, B. W., Enger, E. D., & Ross, F. C. (2008). Integrated science (4th ed.). New York, NY: McGraw-Hill.

Marbles and Surfaces: Guided Inquiry

In considering motion of objects, the force of friction is often overlooked and underappreciated.  In learning about Newton’s three laws of motion the force of friction is not immediately apparent.  The first law states that an object in motion tends to stay in motion while an object at rest tends to stay at rest unless an outside force acts on it (Tillery, Enger, & Ross, 2008).  One of the major forces that apply to stop inertia is friction. The other force is air resistance, although this is in general less than that of the force of friction.  I have often noticed that students coming into my classroom have a good understanding of the basic laws of motion but have trouble with prediction of what will happen based on what they know and have trouble explaining their results.  In this article I will be discussing the completion of a guided inquiry lesson that I was given to complete on how different surfaces affect the momentum of marbles.  I will then discuss issues that occurred during the testing and how I could implement this type of guided inquiry in my classroom.

I looked at this assignment as an opportunity to develop a lesson for my students.  In reviewing the question I thought back to a few pieces of information that I have been given.  In Forces and Motion (Laureate Education, 2010), Osborne was accomplishing a structured inquiry lesson on how far different cars travel.  In this lesson she made a big deal about the wheels and axel types that these cars had and correlated this to the distance that a car can travel.  In this lesson Osborne was trying to establish a correlation between distance traveled and the forces of friction.  This lesson seemed to be successful but the objectives of the class also contained discussions of mass, speed, and inertia and did not cover the applied mathematics of the motion.  Since I teach students that are a little older than Osborne I feel that my students would benefit from a guided inquiry lesson that requires them to use a little more of the math and design their own test.  This will mean that I will only cover the concept of friction in my lesson.  I then reviewed the concept in Tillery, Enger, & Ross (2008) for the application of Newton’s laws that I would be covering.

Next, I formulated a hypothesis that if friction is involved in stopping a marbles momentum, then the more friction that is applied the marble will stop faster.  In this case, more friction would be applied in softer surfaces that allow more of the ball’s surface area to come in contact.  This hypothesis can be supported by a forum (Cognaq, 2008) where a posting says that if friction were not in play then the ball would not roll, but slide down the decline of the hard surface ramp.  This was an interesting thought and one that I had not considered in a very long time.  I liked that I was given time in this experiment to do some independent research on the topic, without this I would not have thought about this intricate point on the evidence of friction besides the ultimate slowing down of the ball.  I probably need to allow my students time to research topics a little more, I can often rush them and they might overlook some of these more detailed discoveries.

The next step was to plan the test.  I decided to use three different surfaces for the test; tile, newspaper, and a towel.  I also used a standard sized marble and a fixed ramp to ensure that the only change in distance traveled by the marble had to do with the surface that it traveled on.  The ramp that I used consisted of two books as the height and a hard bound book as the slope.  I used three replications of the test with each surface types used and obtained a result of 80.5 cm for the newspaper, 125 cm for the tile, and 73.5 cm for the blanket.  When I tested the newspaper I noticed that the folds in the newspaper provided extra resistance that was not really friction.  I believe that if I were to do this test in my class I would modify the materials that I would supply my students to include the option of cardboard since it is flat.  I still think that the use of newspaper would be beneficial since it would teach the students to be more critical of their results.  In the experiment I obtained the results that I was expecting, the harder surfaces allowed the marble to travel farther.

I believe that guided inquiry lessons are extremely beneficial to use in a classroom since students will take more accountability for their laboratory than if they were instructed what to do.  This makes the activity a little higher order thinking (Banchi & Bell, 2008).  This will benefit my students by making them think about the topic a little deeper, have them design a laboratory, and be a little more critical of their procedure and results.  I think the challenge of this type of activity really comes down to students’ acceptance of accountability in their education and willingness to think a little more.  In order to achieve my goals and help students learn the benefit in this I will have to monitor my student groups carefully, place my students in groups according to their skills and abilities (differentiate), and allow them time to think about what to do and to analyze their results.

I thought that this exercise was effective in teaching me the benefits of a guided inquiry lesson, especially in ensuring that I had time to research the topic a little more before planning the experiment.  This is one major lesson that I know now that I have get better at.  There are a few challenges in implementing this type of lesson, most having to do with student motivation.  With good classroom management techniques as well as student knowledge of the benefits of this type of lesson I believe that the challenges can be overcome and I can enable the students to take greater accountability for their education and they can increase their learning in a more meaningful way.

References

Banchi, H., & Bell, R. (2008). The many levels of inquiry. Science & Children, 46(2), 26–29.

Cognaq (2008, October 11). Rotation caused by friction on a sphere. [Discussion group comment]. Retrieved from http://www.physicsforums.com/showthread.php?t=263405

Laureate Education, Inc. (Producer). (2010). Forces and motion. In Exploring the Physical World. Retrieved from http://www.courseurl.com

Tillery, B. W., Enger, E. D., & Ross, F. C. (2008). Integrated science (4th ed.). New York, NY: McGraw-Hill.