Heat Transfer Lesson Plan

Transcription

1 Heat Transfer Lesson Plan I. Benchmarks: P.EN.M.4 Energy Transfer- Energy is transferred from a source to a receiver by radiation, conduction, and convection. When energy is transferred from one system to another, the quantity of energy before the transfer is equal to the quantity of energy after the transfer. II. Objectives: A. Today, I will be teaching how heat is transferred via conduction, convection, and radiation and how this applies to the atmosphere. This is important to understand many weather processes such as wind. B. TLW explain the similarities and differences between conduction, convection, and radiation. TLW analyze how heat is transferred through the atmosphere. C. The learning goals will be assessed through a class discussion as well as the exit slip. III. Anticipatory Set: See Engage below. IV. Objective/ Purpose: Today we will be looking at how heat is transferred by conduction, convection, and radiation. We will see how this heat transfer applies to the atmosphere. By the end of today, you should be able to identify the types of heat transfer and how heat is mostly transferred in the atmosphere. V. Input: A. Task Analysis: a. The student needs to know what the atmosphere is (a mixture of gases that surrounds Earth) as well as what the troposphere is (the first layer of the atmosphere closest to Earth). b. Step by step procedures of the lesson: See the 5Es below. B. Bloom s Taxonomy: a. Knowledge: What are the three types of heat transfer b. Comprehension: Understanding the definitions of heat transfer c. Application: Looking at a situation and determining if the heat transfer is conduction, convection, or radiation. d. Create: Creating your own example of convection, conduction, and radiation. e. Analysis: Breaking down the model for heat transfer in the atmosphere. C. Accommodations: a. Visual: tutorial/ convection demo video b. Auditory: Heat Transfer song c. Tactile: touching the metal versus the plastic chairs to feel conduction d. Students work on a tutorial, which allows them to work at their own pace. e. Students had a choice to work in groups or alone for the tutorial. D. Materials and Methods: a. Instructional Strategies: Lecture, tutorial, discussion, video of a song and demo b. Materials: laptop/ internet connection/ pan/ plastic cutting board/ 2 ice cubes IV. Modeling: Modeled how to determine if something is conduction, convection, or radiation. Modeled heat transfer in the atmosphere by notes on the board/ discussion. VII. Checking for understanding: A. Student s examples of conduction, convection, radiation B. Student responses when reviewing their tutorial worksheet. C. Use the five-finger scale assessment after reviewing the worksheet. D. Exit slip responses VIII. Guided practice: student examples of conduction, convection, and radiation. IX. Independent practice: exit slip may turn into an admit slip for the next day if time is short. X. Closure: Students will be given a heat transfer exit slip.

2 Engage: At the beginning of class, ask students to brainstorm different ways to warm up when you are cold. Have the students share their ideas with the class. Make a class list on the board. The goal is for students to start thinking about heat. Add some examples of your own to the list, if not already on there. Examples include going from the basement to the top floor, going into the sun, standing by a fire, using hand warmers or seat warmers. After the list is made, tell the students that we will be learning about the three ways heat can be transferred, conduction, convection, and radiation. We will then see how heat is transferred in the atmosphere. We will return to this later to identify which examples are conduction, convection, and radiation. Explain: Display the graph that depicts the change in temperature over time of two cups of water that are mixed together. Ask students to interpret the graph by stating the following question: If I mix 1L of warm water with 1L of cold water, what happens to the temperature of both liters of water? Students should respond that the temperature of the hot water will decrease and the temperature of the cold water will increase. Ask students if the temperature will keep changing forever. The students should determine that the temperature will eventually even out. Pass out the Heat Transfer: Conduction, Convection, and Radiation Worksheet. Tell the class that they will take notes on how we define heat. Heat is the transfer of energy from a hot object to a cold object. Heat will always flow from hot objects to cold objects. The total amount of energy before the transfer is the same total amount of energy after the transfer. Convection, conduction, and radiation are all forms of heat transfer. Explore: Allow students to work in groups, pairs, or by themselves, but each person needs his own worksheet. Each group of students needs atleast one laptop with Internet connection. Students will visit the following tutorial online: The students will answer the questions on the worksheet using the tutorial. The tutorial defines heat transfer, conduction, convection, and radiation. The tutorial provides both visual representations and other examples of each type of heat transfer. The teacher will circulate the room to assist students and deter disruptions.

3 Engage: Students can review the previous day s material by watching a song/ rap about heat transfer in the atmosphere. Some new terminology is used in the video, so on the board define diffuses/ diffusion, equilibrium, temperature. The song can be accessed through the following link: Arrange students into groups of four. Display the list of ways students warmed themselves up, include the examples that you added. Ask students to label which examples are radiation, convection, and conduction. Choose one example, such as standing close to a fire, to model for the class. Below is the general thought process to model: So is standing near a fire conduction, convection, or radiation? Well I am obviously not touching the fire, so it cannot be conduction. It cannot be convection because there is not a movement of fluid or gases that is transferring the heat. But I am feeling the heat radiating on me from the fire, so it must be radiation. After modeling, have the students label the examples that are conduction, convection, and radiation. The group must also give an example of each type of heat transfer that is not on the list. The students should write their answers on their bell ringer. After about 5 minutes, have each group share their ideas with the class. Explain: Briefly review the worksheet with the students by going through the tutorial on the overhead projector. Ask students how they answered the questions before revealing the answer to them. Below is an outline to for that includes both the answers to the worksheet and additional key points and examples. 1. What are the three ways that heat is transferred in our environment? Conduction, radiation, convection 2. What is conduction? You can use words or draw a picture. Transfer of heat between substances that are in direct contact with each other. An example of a picture to draw would be someone touching a pot handle. 3. What is a better conductor, air or iron? Why? A good conductor is a material that quickly transfers heat. Iron is a better conductor than air because it transfers heat faster. What is convection? Use words AND draw a picture. Convection is the up and down movement of gases and liquids caused by heat transfer. Ask students why convection occurs. Convection occurs due to differences in density. Students should draw the arrows of warm air rising and cold air sinking. 4. Why does warm air rise and cool air sink?

4 Warm air expands, causing it to become less dense than cold air. Because warm air is less dense, it rises above the cool air 5. What is radiation? Use words AND draw a picture. The transfer of heat by electromagnetic waves through empty space. Students can draw the sun radiating on a house. 6. How does the sun warm the Earth? The sun warms the earth through the radiation of electromagnetic waves. Bring up a picture of the electromagnetic spectrum. Tell students that radiation is energy that comes from a source and travels through space as waves. There are a lot of different types of radiation. The three types that we are going to focus on are ultraviolet, infrared and visible. Ask students what protects us from most ultraviolet radiation (ozone layer). Tell students that we are only able to see the visible light, but the atmosphere gets most of its energy from infrared radiation. Elaborate: First, students will identify types of heat transfer while making predictions and explaining observations for convection and conduction. Convection: Pull up the YouTube video ( that demonstrates convection. Verbally tell the students that the food coloring is inserted into the room temperature water. The boiling hot water is put underneath the container. Pause the video and ask students to write down what they predict will occur. Have students share their ideas. Play the rest of the video. Ask the students why the food coloring is rising. The students should be able to say that as the liquid is heated, it expands, becomes less dense, and rises. Ask students why the food coloring eventually sinks. Students should say that the food coloring sinks because the liquid gets cold, becomes denser, and sinks. Conduction: Have students touch the metal part of the pan, then cutting board. Ask students which is a better conductor of heat and why. The students might say that the cutting board is a better conductor of heat, because it feels warmer to them. Tell the students that both the metal and the plastic are the same temperature because they are sitting in the same room for a long period of time. Ask students to predict what will happen when I put an ice cube on the pan and on the cutting board. After they share some predictions, place an ice cube on both the pan and the cutting board. Ask the students to observe what is happening. Ask the students why the ice melted on the pan faster than on the cutting board. If students are stuck, say that if the metal was not giving heat to the ice cube, what must it been doing? The metal only feels colder because it is conducting the heat from your hand, which is the warmer object. The plastic is a poor conductor is it does not suck the heat from your hand. Therefore the pan sucked the heat from the ice cube, making it melt. Radiation: Turn on a lamp and place your hand away from the lamp, enough to feel the heat. Do not let students do this or they may feel the need to touch the bulb. Ask students what type of heat transfer your are experiencing. Ask students how they came up with that answer. They should say that you were not touching the bulb and that the bulb is the source of light/ energy waves. After all three types of heat transfer are demonstrated, heat transfer in the atmosphere will be modeled through discussion/ notes on the board.

5 Give students a paper of the empty model of the atmosphere. Tell the students that we are going to be modeling heat transfer in the atmosphere. Use the following guiding questions and statements below to complete the model as a class. 1. Ask students, What is the main source of energy? The students should say the sun. Label the sun. 2. Ask students, How does the sun transfer its energy to Earth? (radiation) Draw a large radiation ray to hit Earth s surface. Write and say that 50% of the energy is absorbed by land. 3. Ask students, What else could happen to the radiation from the sun when it meets the Earth s surface? They might say it bounces off. This is called reflection. Draw an arrow from the sun that hits the water and draw it reflecting back into the atmosphere. Write and say that 5% or energy is reflected back into the atmosphere. Also tell students and write on the model that most of the energy that is absorbed actually radiates back into the atmosphere as infrared radiation. Make a note that most of the energy that heats Earth s surface is infrared radiation. 4. Ask students, If only 50% of the sun s energy is absorbed by Earth, what happened to the other 50% of energy? If students are confused, ask students what the atmosphere is made up of. (Gases). Tell the students to think about what happened to the energy when it hit Earth s surface. The gases will do the same thing. The students should then be able to say that the gases absorb energy. Draw an arrow from the sun that stops in the atmosphere. Write and say that 20% of the energy is absorbed by gases. Then draw an arrow from the sun to the cloud that scatters in different directions. Write and say that 25% of the energy is scattered by clouds, gases, and other particles in the atmosphere. Scattered means reflected in all directions. 5. Ask students, The energy from the sun does not heat the surface evenly. Parts of the surface that get hot heat the air just above it. The air will then get warm. What will happen to this air? Students should be able to say that it expands and rises because it is less dense. Draw arrows pointing from the air above the ground up and label it hot. 6. Ask students, What will happen to the air after it rises? The students should say that it gets cold and sinks because it is denser. Draw arrows that point down and label it cold air. 7. Ask students, What type of heat transfer is this? They should be able to say convection. Label this as convection. Write and say that most of the heating of the troposphere comes from convection. After you are done with the model, tell the students that you do not want them to know the percentages, but you want them to have a general idea of what happens to the radiation from the sun, that most of the energy that heats Earth s atmosphere comes from infrared radiation, and that most of the that of the troposphere comes from convection. Evaluate: To assess student understanding of the heat transfer lesson, have students complete the exit slip worksheet.

6 %% Notes:%%% Name Date Heat%Transfer:%Conduction,%Convection,%and%Radiation% % isthetransferofenergyfromahotobjecttoacoldobject.heatwillalways flowfrom objectsto objects.thetotalamountofenergybeforethe transferisthe totalamountofenergyafterthetransfer.convection,conduction, andradiationareallformsofheattransfer. % Online%Activity% Directions: Gotogoogle.com.Typein WiscHeatTransfer. Clickonthefirstlink.Scroll downtothebottom,andyouwillseeananimatedactivity.usethisactivitytohelpanswer thefollowingquestions. 1. Whatarethethreewaysthatheatistransferredinourenvironment? 2. Whatisconduction?UsewordsANDapicture. 3. Whatisabetterconductor,airoriron?Why?

7 4. Whatisconvection?UsewordsANDdrawapicture. 5. Whydoeswarmairriseandcoolairsink? 6. Whatisradiation?UsewordsANDdrawapicture. 7. HowdoesthesunwarmtheEarth?

8 %% Notes:%%% Heat%Transfer:%Conduction,%Convection,%and%Radiation%Rubric%% % Heatisthetransferofenergyfromahotobjecttoacoldobject.Heatwillalwaysflowfrom hotobjectsto%coldobjects.thetotalamountofenergybeforethetransferisthesame%total amountofenergyafterthetransfer.convection,conduction,andradiationareallformsof heattransfer. Online%Activity% Directions: Gotogoogle.com.Typein WiscHeatTransfer. Clickonthefirstlink.Scroll downtothebottom,andyouwillseeananimatedactivity.usethisactivitytohelpanswer thefollowingquestions. 5. Whatarethethreewaysthatheatistransferredinourenvironment? Conduction,radiation,convection 6. Whatisconduction?Youcanusewordsordrawapicture. Transferofheatbetweensubstancesthatareindirectcontactwitheachother. 7. Whatisabetterconductor,airoriron?Why? Agoodconductorisamaterialthatquicklytransfersheat.Ironisabetterconductorthan airbecauseittransfersheatfaster.

9 8. Whatisconvection?UsewordsANDdrawapicture. Convectionistheupanddownmovementofgasesandliquidscausedbyheattransfer. Convectionoccursduetodifferencesindensity. 9. Whydoeswarmairriseandcoolairsink? Warmairexpands,causingittobecomelessdensethancoldair.Becausewarmairisless dense,itrisesabovethecoolair. 10. Whatisradiation?UsewordsANDdrawapicture. Thetransferofheatbyelectromagneticwavesthroughemptyspace. 11. HowdoesthesunwarmtheEarth? Thesunwarmstheearththroughtheradiationofelectromagneticwaves.

10 % Part A: Free Response Name Heat%Transfer%Exit%Slip% Date What are the three types of heat transfer? How are they different from each other? Part B: Fill in the blank. 1. The atmosphere is heated mostly by radiation from the sun. 2. Cold air sinks because it is more than warm air. 3. Heat in the troposphere is mostly transferred by. Part C: Identify the type of heat transfer that is described An oven that circulates hot air 6. A spoon in hot cocoa becoming hot

11 Brainstorm*a*list*of*ways*that*you*warm*up*when* you*are*cold.*

12 If*I*mix*1L*of*warm*water*with*1L*of*cold*water,*what*happens*to* the*temperature*of*both*liters*of*water?*

13 Heat*Transfer* Heat%is*the*transfer* of*energy*from*a*hot* object*to*a*cold* object.*** Heat*will*always*flow* from*hot*objects*to* cold%objects.***

14 The*total*amount*of*energy*before*the*transfer*is* the*same*total*amount*of*energy*aber*the* transfer.* * * * * * ConvecEon,*conducEon,*and*radiaEon*are*all* forms*of*heat*transfer.*

15 Heat*Transfer*Song* * hgp:// v=7y3mfagvn1c**

16 Checking%for%Understanding % Which*of*the*following*are*examples*of*conducEon,* conveceon,*or*radiaeon?* Drinking*cocoa* Hugging*a*dog*or*cat* Stand*by*fireplace* Using*handwarmers* Go*upstairs* Stand*by*a*heater* Go*into*the*sun* In*your*groups,*come*up*with*one*more*examples*for* radiaeon,*conveceon,*and*conduceon.*

17 HEAT*TRANSFER* Please*take*out*our*Heat*Transfer*Notes/* Worksheet.* We*will*review*the*informaEon*together.*

18 Heat*Transfer* 1. ConvecEon,*conducEon,*radiaEon* 2. ConducEon*is*the*transfer*of*heat*between* substances*in*direct*contact*with*each*other.* 3. *A*good*conductor*is*a*material*that*quickly*`transfers* heat.**iron*is*a*beger*conductor*than*air*because*it* transfers*heat*faster.* 4. ConvecEon*is*the*up*and*down*movement*of*gases* and*liquids*caused*by*heat*transfer.**conveceon* occurs*due*to*differences*in*density.* 5. When*air*is*heated,*it*expands.**It*is*now*less*dense* than*colder*air.**less*dense*warm*air*rises*above*the* denser*cold*air.*

19 Heat*Transfer* RadiaEon*is*heat*transfer*caused*by* electromagneec*waves*travelling*through* space.*these*waves*transfer*heat*to*objects* that*absorb*it.* The*sun*warms*the*Earth*through*radiaEon.** Earth*absorbs*its*electromagneEc*waves.** Most*of*the*energy*that*heats*the*atmosphere* comes*from*infrared*radiaeon.*

20 The*ElectromagneEc*Spectrum* RadiaEon*is*energy*that*comes*from*a*source,*like*the*sun,*and* travels*as*waves* There*are*a*lot*of*different*types*of*waves*that*are*put*onto*the* electromagneec*spectrum.* Most*of*the*energy*that*heats*the*atmosphere*is*in*the*form*of* infrared%radia6on.%

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22 DemonstraEon* hgp:// * What*do*you*think*will*happen*when*I*put*a*cup*of* hot*water*below*the*beaker?* * What*really*happened?* * Why*did*it*happen?*