Activities: Conduction

Hot Cup

Construction Context
Houses are well insulated to keep heat in or to keep heat out.  Conduction and convection play rolls in allowing a cold room to become warm on summer days, or in allowing a warm room to become cold on a winter night.  Radiation plays a roll when a house is in contact with direct sunlight.

Materials
* Styrofoam cups (with lids)
* A temperature sensor

Activity Description
Test a plain Styrofoam cup with a lid using the following test procedure:

1. Put 100 g of water in the cup.
2. Make sure your starting temperature is not less than 70oC (verified by teacher)
3. Measure the temperature of the cup every minute until it drops 5oC (verified by teacher).
4. Calculate the heat lost by the cup.
5. Calculate the heat lost per minute.

Design a cup that you think will be more effective than a plain Styrofoam cup.  Before building the cup you must submit a detailed drawing including a cross section that shows your design.  You also must identify in writing or verbally which features will reduce heat flow.

Science Concepts
Conduction and Convection

Next Generation Science Standards
Scientific and Engineering Practices:
- Planning and carrying out investigations
- Constructing explanations and designing solutions

Crosscutting Concepts:
- Systems and system models
- Energy and matter: Flows, cycles and conservation
- Structure and function

Speed Melting

Construction Context
Conduction, convection and radiation are all methods for transferring heat energy from one thing to another.  Buildings are constructed to prevent all three of these from effecting the temperature of the inside space.

Materials
- Frying pan and hot plate
- Hair dryer
- Heat lamp
- Optional materials: Pyranometer

Activity Description
Melt an ice cube using conduction, convection, and radiation. To cover the three methods, use a frying pan for the conduction based melt, a hair dryer for the convection based melt and a heat lamp for the radiation based melt.

Science Concepts
Convection, conduction, and radiation

Next Generation Science Standards
Scientific and Engineering Practices
- Asking questions/defining problems
- Planning and carrying out investigations

Crosscutting Concepts
- Cause and effect: Mechanism and explanation

Reflection Questions
1. What happens if you hold the hair dryer closer or farther from the ice cube?
2. What happens if you hold the heat lamp closer or farther from the ice cube?
3. What happens if the frying pan’s heat source is turned up or down?
4. Do the three methods scale the same?  (I.E. does putting the heat lamp 1 inch away yield the same effect as turning the frying pan on high?)

Everyday Heat Transfer

Construction Context
Some of our everyday environments are constructed for us as buildings. This project has concentrated on buildings. Other environments have been “built” for us as clothing, appliances for cooking, cars, roadways, and bridges. Our environment is filled with technologies constructed for our convenience and comfort. Heat transfer is involved with how many of these things work. For example, the clothing we wear has been designed and constructed to keep us warm or cool or just plain comfortable throughout the day.

Materials
*  These pictures will guide the activity and discussion
* Optional item:
- Infrared Thermometer

Activity Description
Use the pictures to guide discussion about how heat transfer is involved in our everyday lives.  These pictures were borrowed from Energy Sleuth from the Maine Mathematics and Science Alliance <http://www.powersleuth.org/>.

For each picture you can ask students to describe the role of conduction, convection, and radiation.  In many cases, all three concepts of heat transfer are involved.

A key point for each pictured situation is to describe where the heat comes from and where it goes.  Heat is always on the move.  Some things slow it down like insulation but others allow it to move easily like a cooking pan.

The picture of the ice cream cone will be interesting to discuss.  Instead of looking at a source of heat, like a fire, we are looking at an object that is absorbing heat from the air.  Students may want to talk about the ice cream losing “cold” to the air.  This may require some open discussion and students offering several, often conflicting, explanations to start a process of rethinking this situation in terms of heat flow.

The person with the scarf offers different kind of challenge.  Instead of gaining heat from the air, the scarf slows the heat transfer from the body.  Students may want to revisit the [incorrect] idea that the scarf keeps the cold out.  Again, getting students to generate and share and critique explanations will be important.  But how does it slow heat transfer?  Challenge students with this point.  The scarf is an insulator by wool being a poor conductor of heat and by trapping air near the skin so that there is no convection to circulate body heat away.

Science Concepts
Conduction with connections to radiation and convection

Next Generation Science Education Standards
Scientific and Engineering Practice
- Asking questions (for science) and defining problems (for engineering)
- Constructing explanations (for science) and designing solutions (for engineering)

Crosscutting Concepts
- Systems and system models
- Energy and matter: Flows, cycles, and conservation
Structure and function

Reflection Questions


  • What is the difference between “heat” and “cold”?

  • How do we feel “heat”?  How do we feel “cold”?

  • Why do some things “feel” cold and some “feel” warmer even though they are the same temperature?

  • Think of various kinds of clothing and describe how they function with respect to conduction, convection, and radiation.

Wall R Value

Construction Context
We spend the most money for energy heating and cooling our home.  Insulation reduces that cost and saves money.  The effectiveness of insulation is designated by its “R” value.  The higher the R Value the better the insulation.  “R” refers to the “resistance” to heat flow.  See http://www.cellulose.org/HomeOwners/WhatR-valueMean.php for more information about insulation.  Understanding how well a home is insulated is complicated by the fact that a wall in your home is usually a combination of wall-framing, windows, doors, and other interruptions in the insulation.

Optional Materials
Infrared Thermometer

Activity Description
This activity can be conducted as a qualitative analysis of the number and kind of interruptions in the walls of a room or house.  For example, students count the number of windows, doors, vents, and electrical wall outlets in the outside walls of their home.  This provides a qualitative assessment of home insulation.

A more meaningful assessment of insulation would be to compute the total square feet of wall interruptions and of what type: windows, doors, vents, and electrical wall outlets.  Students could compute the total square feet of outside walls and then compute the ratio of square feet of interruptions to the total wall area.

Included in this activity is a description of computing the total R Value of a wall considering typical features of a wall.  This quantitative treatment of the problem can provide the basis for a rich discussion of heat flow through walls and energy efficiency in a home or building.  Such a discussion shows the interconnection of science concepts in real-world problems.

Science Concepts
Heat Conduction [relations to Convection and Radiation]

Next Generation Science Education Standards
Scientific and Engineering Practices
- Asking questions (for science) and defining problems (for engineering)
- Using mathematics and computational thinking

Crosscutting Concepts
- Patterns
- Scale, proportion, and quantity
- Energy and matter: Flows, cycles, and conservation

Discussion Questions
1.) Ask students to reflect on the effectiveness of insulation in a home.  Guide discussion so that students come up with the effect of windows, vents, etc. on home insulation and energy efficiency.
2.) What can be done to improve efficiency after introducing insulation in the walls?  (e.g. thermal pane windows, Low-E glass, plug covers for outlets, heavy window covers, etc.)
3.) Ask students to interpret what the ratio of wall-interruptions to wall area tells you about energy efficiency.  (e.g. the higher the ratio the poorer the energy efficiency.
4.) Watch the classroom video that examines the effect of insulation around a box on heat flow out of a box with and without insulation.

Heat Resistant Glass

Construction Context
Some of our everyday environments are constructed for us as buildings.  This project has concentrated on buildings.  Other environments have been “built” for us as clothing, appliances for cooking, cars, roadways, and bridges.  Our environment is filled with technologies constructed for our convenience and comfort.  Heat transfer is involved with how many of these things work.  For example, in the kitchen there are a large number of appliances and other equipment where heat transfer is central to how they work.

Materials
CorningWare or Pyrex cookware
Flour

Activity Description
“Cook top” ranges have a special glass that covers the entire surface of the range.  The electric heating elements are under this glass.  A major feature of this design is that you have smooth surface to clean.  However, you also have surface that can be touched in the areas not directly affected by the heating elements.  This suggests to me that heat transfer is by radiation to the cook top and/or the pan.  The cook top does not conduct heat very well.  It is, I think, derived from material like CorningWare or Pyrex, which can withstand enormous variations in temperature. It evolved from materials originally developed for a U.S. ballistic missile program, and Stookey's research involved heat resistant material for nose cones.  Here is some interesting reading:

http://www.bookrags.com/research/glass-heat-resistant-woi/

You can conduct this activity as an investigation.  You could stimulate questions from students by talking about pans were food sticks when you cook.  You can describe noticing an interesting pattern on the bottom of a particular pan.  What caused this pattern?

Here is the activity and an explanation.  For an investigation, generate discussion from students and suggestions for further testing so that they construct the explanation.

Place a CorningWare bake ware on the stove.  Sprinkle flour over the bottom of the CorningWare and turn on the heating element or gas.  The flour will brown in the shape of the element because CorningWare does not conduct heat very well.  It gets hot where the element is but does not spread the heat.  It is good for going from freezer to oven but on the stove, you need something like water in the container to circulate the heat.

Science Concepts
Conduction [with connection to convection and radiation]

Next Generation Science Education Standards
Scientific and Engineering Practices:
- Developing and using models
- Planning and carrying out investigations
- Constructing explanations (for science) and designing solutions (for engineering)
- Engaging in argument from evidence

Crosscutting Concepts:
- Patterns
- Cause and effect: Mechanism and explanation
- Energy and matter: Flows, cycles, and conservation
- Structure and function

Reflection Questions
- Of what benefit is it to make heat resistant glass?
- What other features would be helpful to design into glass?  [think of windows; think of glass in big buildings; think of different kinds of situations where you need protection]
- What is the difference between glass and plexiglass?

Chemical Reactions in Construction

Construction Context
This activity fits equally well in the Thermodynamics and the Mechanics & Materials units. Chemical reactions are important in construction in several places, including concrete, welding, paints, adhesives, solvents, corrosion (rust), batteries, and combustion. Helping students understand that chemistry is related to all these diverse topics will support their understanding selected chemistry concepts and better understand principles of construction.

Materials
For chemistry teachers doing the iodine clock reaction:
* Beakers or test tubes
* The following chemicals:
- 1.0 liters of 0.1M potassium
- 1.0 liters of 1% starch solution
- 0.5 liters of 0.25M sodium bisulfate
* Optional materials:
Infrared Thermometer
Temperature Sensor

Activity Description
The document Teaching Chemical Reaction in Construction provides multiple examples of how chemical reactions applied in context of construction technologies. Each example can be the basis for a classroom activity or demonstration. The greatest benefit of these examples will come when there is a partnership between chemistry and construction professionals. This can happen when there is both a chemistry and construction teacher in the building. With collaboration between chemistry and construction teachers these activities and demonstrations can be set up as small investigations. Using student experience with rust, drying time of paint, and watching construction sites, teachers guide students into expressing interesting questions. The examples can be used to prompt students to use their newly developing chemistry knowledge to explain the behavior of these materials.

Science Concepts
- Conduction
- Oxidation & Inert Gases
- Proportions and Ratios
- Rates of reaction

Next Generation Science Education Standards
Scientific and Engineering Practices
- Asking questions (for science) and defining problems (for engineering)
- Constructing explanations (for science) and designing solutions (for engineering)
- Engaging in argument from evidence

Crosscutting Concepts
- Cause and effect: Mechanism and explanation
- Scale, proportion, and quantity
- Stability and change

Reflection Questions
By going to the National Science Teacher Association web site and searching for the September 2001 article, Concrete Inquiry, you will find additional ideas on this topic. http://www.nsta.org/highschool/

Other useful information can be found at the Portland Cement Association website.  Clicking on "Concrete in the Classroom" will take you to several lesson plans.  However the page connects you to information about concrete presented in several formats.  This site is excellent for student research. http://www.cement.org/basics/index.asp