Heat on the Move

Flesh out concept that convection is a more efficient, faster method, for heat then conduction. Heat being transferred via conduction is a major force that drives many of the processes on Earth, i.e. weather, ocean currents and plate tectonics.

I will be doing this activity during a year-long Geology and Astronomy Course taught to 8th grade students who have covered the MA Science Curriculum Frameworks in Physical Sciences, Grades 6-8 in 7th grade. In 7th grade, students were exposed to the following Heat Energy Learning Standards A) Recognize that heat is a form of energy and that temperature change results from adding or taking away heat from a system. B) Explain the effect of heat on a particle motion through a description of what happens to particles during a change in phase C) Give examples of how heat moves in predictable ways, moving from warmer objects to cooler ones until the objects reach equilibrium. Students will also have been exposed to the 3 means of heat transfer, conduction, convection and radiation. (One of the goals of this activity is to review the Heat Energy Learning Standards and Heat Transfer Ideas.) Ideally, the hands-on experiment part of this activity will be done with a class of 20 - 24 students, divided into groups of four. The popcorn demo and class discussion will take place during the 1st of 3 - 47 minute classes. On the second day, in small groups of 4, the convection vs. conduction experiment and data collection will take place. During the third class period, I will repeat the experiment and then facilitate a class discussion of students' results. Students will have already had lots of practice at looking for patterns within data. They will have practiced this skill during our Nature of Science Unit. I think this activity would be easily adaptable to different ages and/or student with varied knowledge bases.

Background

(This is the background information that my students will be bringing to this experience, but depending on your goals; students do NOT need to have these understandings.) Students will have some basic understanding of the Phases of Matter - solids, liquids, and gases. Students will have some understanding of what makes a "solid" a "solid." Solid is matter that maintains its volume and holds its shape. Liquid is matter that maintains its volume but can't hold its shape (or takes the shape of its container.) A gas is matter that neither maintains its volume nor maintains its shape. Students will have practiced at collecting data and looking at lots of data sets to try to tease out and identify patterns. Students will have heard the words conduction, convection and radiation - but most likely have varying understandings of these concepts.

In-Class Activities

Day 1
Popcorn Demo (Activity developed by Amy Vashak)
1) Explain to students that I will be making popcorn using three different methods. As I am making the popcorn using the three methods, students are to draw and label the set-up of each method of popcorn making and below their diagram of the set-up they are to record observations, what they see, hear and smell. The first way I will make popcorn is to place a bag of microwave popcorn in a microwave oven. The second method of popcorn making will be using an air popper. The third method will be to place a pan on a hot plate. Pour a little oil in the bottom of the pan and cover until oil is heated, but not smoking. Then pour some popcorn in the pan, cover again, and jostle the pan over the hot plate until the popcorn pops.
2) After the demo, I will ask students, with a partner, to make a list of what these three methods had in common and what was different with the three methods.
3) We will then have a 5 minutes brainstorming session about all the similarities and differences they noticed between the 3 methods. I will record students' observations on a large piece of white paper that I will then hang in the class so we can refer to it at a later time.

Matter vs. Energy Class Clarification Conversation
1) I will write on the board the words Gas, Liquid, Solid.
2) Together with the class, we will brainstorm examples of each.
3) I will then ask students, "What are gases, liquids, and solids made of?" I will listen to students ideas and write them on the board. When I have done this activity in the past I find students need some clarification on the differences between the words atoms, molecules and matter.
4) I will refer to the periodic table and explain that this chart is a list of different kinds of atoms based on the number of protons an atom has. I will remind students that the word molecule describes when two or more atoms are bonded together. Finally, I will clarify that anything made of atoms, which includes all gases, liquids, and solids, is called matter.
5) I will then write the word heat energy on the board and clarify that heat energy is not matter. Energy gives movement to atoms and molecules.
6) I will also clarify that heat energy only moves in one direction, from atoms/molecules with more heat energy to atoms/molecules with less heat energy.

Day 2

3 Possible Experiments – I need to spend some time playing with these materials to see if any of them will yield the results I am looking for – a way to show that heat moves quicker when moving via convection as opposed to conduction.

Experiment 1

The idea for this experiment would be to graph the temperature of the solid as it is heated up, melts and continues to a boil. I was hoping when the data is graphed, that the slope of the line after the phase change would be steeper then the slope of the line before the phase change.

1) Students will be given safety glasses, a hot plate, oven mitt, thermometer, a beaker with a substance that is solid at room temperature, but melts at a fairly low temperature. (Butter, wax, chocolate...I need to research this a bit more.)

2) Students will place the thermometer into the substance and measure the starting temperature.

3) Students will then turn on the hot plate to a specified temperature.

4) Students will be asked to draw and label the set-up. Students will be asked to record the temperature every 30 seconds and make observations. Students will be prompted to note when the solid appears to begin melting and when the solid appears to be entirely melted into a liquid.

For homework, students will be asked to graph their results (time vs. temperature.) Students will also be asked to make sure their observations and data tables are complete.

Experiment 2

The idea for this experiment would be for students to compare the speed of two beakers of water that are being heated. The control variable would be a disc of material (that will not melt and to be determined), that is placed between one of the beakers and the hot plate. Students would record the temperatures of both beakers. I was hoping when the data is graphed, that the slope of the line for the beaker without the disc of material would be steeper then the slope of the line of the beaker with the disc of material placed between the beaker and hot plate.

1) Students will be given safety glasses, an eyedropper, food coloring, set of colored pencils, two hot plates, two thermometers, an oven mitt, two beakers filled with same volume of water, a mechanism for holding the thermometers in place and a disc of material.

2) Students will place one beaker on directly on one hot plate. Students will place the disc of material on the top of the second hot place and place the second beaker on top of this disc.

3) Students will then set up each thermometer into the water so that just the bottom of the thermometer is submerged below the surface of the water.

4) Students will let the water stand until the water seems still.

5) Students will then use the eyedropper to carefully place one drop of food coloring on the bottom of each beaker, as a way of tracking the water's movement.

6) Students will then turn on the hot plates to a specified temperature.

7) Students will be asked to draw and label the set-up. Students will be asked to record the temperature every 30 seconds and make observations. Students will be prompted to note the movement of the food coloring.

For homework, students will be asked to graph their results (time vs. temperature.) Students will also be asked to make sure their observations and data tables are complete.

Experiment 3

This is an interesting idea I have for an experiment but I am not sure yet, where it fits in. The idea of this experiment would be to see how convection currents would move through layers of liquids with varying viscosities or densities.

1) Students will be given safety glasses, an eyedropper, food coloring, set of colored pencils, a hot plate, thermometer, an oven mitt, a beaker filled with two liquids that are layered on top of one another, i.e. fresh water on top of very salty water, water on top of corn syrup.

2) Students will place the beaker directly on the hot plate.

3) Students will let the beaker stand until the liquids seem still.

4) Students will then use the eyedropper to carefully place one drop of food coloring on the bottom of the beaker, as a way of tracking the liquids' movement.

5) Students will then turn on the hot plates to a specified temperature.

6) Students will be asked to draw and label the set-up. Students will be asked to record an observation every 60 seconds, especially the movement of the food coloring.

For homework, students will be asked to make sure their observations and data tables are complete.
Day 3
Class model of moving heat energy
I will have 10 students line up shoulder to shoulder. I will describe to students that Student "A" is a molecule who has lots of heat energy and is going to pass it along to "molecules" with less heat energy. I will describe that the slap (clapping of two students' hands together) will represent the passing of this energy from one molecule to another. I will explain that the students lined up are molecules "stuck" in a solid. So the clap or "heat energy" can be passed along, but students are not allowed to move their feet. I will use a stop watch to time how long it takes for the slap to be passed from student "molecule" to student "molecule." I will have my lined up students try to pass the slap, with planted feet, as fast as they can.
Now I will tell the students that Student A is not longer a solid, but a liquid, therefore she can use her legs. Now I ask Student A to pass along her heat energy "slap" with the other students who are lined up. I will time again. I am thinking this second time, because student A can move herself and high-five students as she runs by them; this will be much quicker. (I am still working out this model.) (But I started to think, that when I get to my Seasons Unit, to represent heat transfer via radiation, I could have two students standing on opposite ends of my classroom and make eye contact to pass a clap to one another.)

Looking at Data
On a graph on my overhead projector, I will have one student from each group come up and graph their results, each using a different color marker. I will ask students if they notice any patterns in the data. Depending on how the experiments go, I may explain to them the concept I am trying to show them, that heat should get transferred quicker via convection because the molecules can move around to share their energy as opposed to molecules being, "stuck in place," as they share their heat energy.
(This is still in development, depending on which experiment, hopefully, I find successful.)

Reading
Together, students and I will read about Heat Transfer, specifically Conduction and Convection. (Reading is still being developed.)
I will use this opportunity to model some reading strategies for reading scientific information. I.e. Read through entire article one time, then read through a second time, and in the margins write a sentence, in their own words, next to each paragraph that summarizes the main idea of that paragraph.


At Home Assignments
Day 1
Review of Vocabulary: solid, liquid, gas, atom, molecule, matter and heat energy

Day 2 - For any of the three experiments
Be sure that data table and graph is accurate and labeled completely.
Be sure observations are readable, clearly articulated and all pronouns are replaced. (To help students clarify their own ideas, I do not students to use pronouns in their writing. In any labs or writing assignments that I give, students are prompted to replace pronouns with the noun that the student meant. I.E. Instead of "it," did you mean the water, temperature, food coloring, heat, beaker?)
Complete conclusion questions - to be developed as I figure out which lab will work best.

Day 3
Questions on reading on convection and conduction. (I need to develop this reading and questions.)

Materials

Day 1
Materials for Class

• Microwave Oven
• Bag of Microwave Popcorn
• Hot Plate
• Pan with Cover
• Oven Mitts
• Oil
• Popcorn
• Air Popper
• Large Piece of Paper
• Classroom Size Periodic Table - hanging in classroom

Materials for each student:

• Student Notebooks
• Pen or Pencil

Day 2
Experiment 1
For each student

• Lab description
• Graph paper
• Safety Glasses
• Oven Mitt
• For each group of 4
• Hot Plate
• Beaker
• Thermometer
• A substance that is a solid at room temperature but will melt at a fairly low temperatures. Some ideas I have: marshmellow, butter, wax, chocolate.
  

Experiment 2
For each student

• Lab description
• Graph paper
• Set of colored pencils
• Safety Glasses
• Oven Mitt
• For each group of 4
• 2 Hot Plates
• 2 Beakers
• 2 Thermometers
• Disc of material
• Water
• Food Coloring
• Eye dropper
• Clamping system for Thermometers

Experiment 3
For each student

• Lab description
• Graph paper
• Set of colored pencils
• Safety Glasses
• Oven Mitt
• For each group of 4
• 1 Hot Plates
• 1 Beakers
• 1 Thermometers
• Two liquids of varying densities
• Food Coloring
• Eye dropper
• Clamping system for Thermometer

Day 3
For class:

• Stop watch
• Reading on convection and conduction heat transfer (To be developed)

Standards

MA Science Curriculum Frameworks, published 2006
Earth and Space Science, Grades 6-8
Heat Transfer
3. Differentiate among radiation, conduction, and convection, the three mechanisms by which heat is transferred through the Earth's system.*
4. Explain the relationship among the energy provided by the sun, the global patterns of atmospheric movement, and the temperature differences among water, land and atmosphere
Earth's Structure
2. Describe the layers of the earth, including the lithosphere, the hot convecting mantle, and the dense metallic core.
Physical Sciences (Chemistry and Physics), Grades 6-8
Heat Energy
14. Recognize that heat is a form of energy and that temperature change results from adding or taking away heat from a system.*
16. Give examples of how heat moves in predictable ways, moving from warmer objects to cooler objects until they reach equilibrium
Earth and Space Science, High School
SIS3. Analyze and interpret results of scientific investigations
- Present relationships between and among variables in appropriate forms *
- Represent data and relationships between and among variables in charts and graphs.*
- Use appropriate technology and other tools.*
Mathematical Skills from MA Mathematics Curriculum Framework through grade 8
- Construct and use tables and graphs to interpret data sets.*
- Measure with accuracy and precision.*
- Use Celsius and Kelvin scales.

*Primary Standards being addressed

Completion of all at-home assignments
Accurate collection of data
Accurate plotting of data on graphs that are labeled correctly
Participation in class discussion of observations and discussion questions

Wonderful Popcorn Demo developed by Amy Vashak at http://littleshop.physics.colostate.edu/TeacherWorkshops/Submissions/Energy/HeatTransfer.pdf
The following websites helped me with clarifying my own ideas about heat:
http://en.wikipedia.org/wiki/Heat_transfer_efficiency
http://www.woodrow.org/teachers/esi/2001/Princeton/Project/zerba/activities/activities.htm
http://www.brighthub.com/engineering/mechanical/articles/48503.aspx
http://coolcosmos.ipac.caltech.edu/cosmic_classroom/light_lessons/thermal/transfer.html
http://www.brighthub.com/engineering/mechanical/articles/62074.aspx
http://www.sparknotes.com/testprep/books/sat2/physics/chapter12section1.rhtml

This YouTube Video is a Bill Nye the Science Guy Clip of Heat Transfer.
http://www.youtube.com/watch?v=f1eAOygDP5s&feature=related

I also used various high school and college physics textbooks to find "kid friendly" descriptions of vocabulary and concepts taught.