Heat transfer through conduction, convection and Radiation. Grade 7 Science

1
Heat transfer through conduction, convection and
Radiation.Grade 7 Science

• Concept Presentation
• Initha Subramaniam OISE/UT
• Instructors Dr. Marty Zatzman and Janine
  Extavour

2
Overview

• Curriculum Expectations.
• Prior knowledge on the topic.
• Misconceptions.
• Demonstrations / Experiments.
• Societal issues that can be discussed in class.
• Safety considerations.
• 5 day lesson plan.
• Placement of the concept within the unit.
• Place in the Curriculum.
• Advance preparations/ materials.
• Assessment (A) Evaluation (E).
• Learning styles (LS) / Multiple intelligence
  (MI).
• Differentiated Instruction.
• References

3
Grade 7 Heat UnitCurriculum Expectations

• Fundamental concept Energy transfer
• Big idea Heat is a form of energy that can be
  transformed and transferred. These processes can
  be explained using the particle theory of matter.
• Overall Expectations
• 2. Investigate ways in which heat changes
  substances, and describe how heat is transferred.
• 3. Demonstrate an understanding of heat as a form
  of energy that is associated with the movement of
  particles and essential to many processes within
  the earths systems.

4
Specific Expectations

• 3.1 Use the particle theory to compare how heat
  affects the motion of particles in solids,
  liquids and gases.
• 3.3 Use particle theory to explain the effects of
  heat on volume of solids, liquids and gases.
• 3.4Explain how heat is transmitted through
  conduction.
• 3.5 Explain how heat is transmitted through
  convection.
• 3.6 Explain how heat is transmitted through
  radiant energy.
• 2.4 Use scientific inquiry and experimentation
  skills to investigate heat transfer through
  conduction, convection and radiant energy.
• 2.5 Use appropriate science and technology
  vocabulary, including heat, temperature,
  conduction, convection and radiation in oral and
  written communication.
• 3.7 Describe the role of radiation in heating and
  cooling the earth, and explain how greenhouse
  gases affect the transmission of radiated heat
  through the atmosphere.

5
Grade 9 Earth and Space Climate Change

• Overall expectations
• D1. Analyze some of the effects of climate change
  around the world, and assess the effectiveness of
  initiatives that attempt to address the issue of
  climate change.
• Specific Expectations
• D3.2 Describe and explain heat transfer in the
  hydrosphere and atmosphere and its effects on air
  and water currents.
• D3.3 Describe the natural green house effect.

6
Day 1. solid particles

• Held tightly and packed fairly close together -
  they are strongly attracted to each other.
• Have fixed positions but they do vibrate.
• Expands when heated.

7
Liquid Particles

• Fairly close together with some attraction
  between them.
• Able to move around in all directions but
  movement is limited by attractions between
  particles

8
Gas Particles

• Have little attraction between them.
• Free to move in all directions and collide with
  each other and with the walls of a container and
  are widely spaced out.

9
Prior Knowledge

• kinetic Energy All moving objects have this type
  of energy.
• Particles moving faster greater kinetic
  energy.
• Particles moving slower slower kinetic energy.
• When particles move and collide they speed up or
  slow down.
• Temperature measures the average kinetic energy
  of particles

10
What happens when particles are heated

• When particles are heated they go through a
  change of state.
• Heat Transfer of energy from a particle of a
  warmer object to a particle of a cooler object.
• When heating an object energy is transferred to
  the particles of the object.

11
Change state of matterand how is thermal energy
transferred

• Experiment Expansion and Contraction of
  particles.
• Expansion balloon fasten on a volumetric flask
  set inside a beaker of hot water.
• Contraction Balloon fasten on a volumetric flask
  set inside a beaker of ice water.

12
Note to self

• Give the class candies to earn their votes.
• Mmmmm . Candies make everything better.
• You tube http//www.youtube.com/watch?vVzE_IPeduj
  cfeaturerelated

13
Day 2 Making soup to demonstrate conduction

• Conduction happen when two substances are
  touching. The particles of one substance collides
  with particles of another substance or with each
  other. Thermal energy is transferred. Metals good
  conductors.

14
Day 3 Convection current when boiling water

• Convection is the movement of gases or liquids
  from a cooler area to a warmer area.
• Example cooking soup on the stove.
• The warmer soup moves up from the heated area at
  the bottom of the pan to the top where it is
  cooler.
• The cooler soup then moves down to take the
  warmer soup's place. The movement is in a
  circular pattern within the pan.

15
Day 4 Radiant energy

• Radiation is the transfer of heat energy through
  empty space.
• Energy travels from the sun to the earth by means
  of electromagnetic waves.
• Shorter wavelength higher energy
• Darker-colored objects absorb more visible
  radiation thus becoming good insulators of
  thermal energy.
• whereas lighter-colored objects reflect more
  visible radiation.
• Every surface on earth absorbs and reflects
  energy at varying degrees, based on its color and
  texture.

16
Common misconceptions

• Particles get bigger when they are heated.
• Convection current forms only when a substance is
  boiled.
• At night time land and water cool down at the
  same rate.
• All dark coloured objects are good insulators of
  thermal energy.

17
Misconception 1Particles get bigger when heated.

• Scientifically incorrect.
• Heat energy flows through a region of high
  temperature to a region of low temperature when
  the particles collide.
• This is the process of conduction.
• When particles carry thermal energy they do not
  get bigger but take up more space (expand
  slightly).

18
Experiment Testing for particle expansion

• Ball and ring experiment to explain conduction.
• The sequence used to heat up the objects
• RT ball and RT ring
• Hot ball and RT ring
• Hot ball and hot ring
• RT ball and hot ring
• Explain the observations in terms of the motion
  of the metal particles in the ball and ring.
• Make statements describing the sizes in relation
  to the ball and ring at different temperatures.
• (RT Room Temperature)

19
Misconception 2Convection current forms only
when a substance is boiling.

• When fluid or gas particles are warm they expand
  and become less dense in mass.
• They rise from the bottom moving upwards towards
  the surface .
• As warm particles reach the top layer they push
  down the colder particles (greater in mass) down.
  
• The process continues in a cycle .
• However cooling particles from above will also
  produce convection current.
• Both warm gas and fluid particles transfer
  thermal energy through convection current.

20
Experiment Convection in warm water.

• Plastic container with RT water supported by four
  Styrofoam cup.
• Place a drop of red food coloring at the bottom
  of the water.
• Place blue coloured ice cubes at the top
• Place a cup of hot water at the bottom of the
  food coloring.
• Observe and discuss results.

21
Misconception 3Gases, liquids and solids heat up
at the same rate and release thermal energy at
the same rate
Demo www.youtube.com/watch?vgM0d3fGew-0
22
Land and Sea Breeze

• Convection currents are noticeable near the
  ocean, large lake, or other appreciable area of
  water.
• During the day
• land heats faster than water, so the air over the
  land becomes warmer and less dense.
• It rises and is replaced by cooler, denser air
  flowing in from over the water. This causes an
  onshore wind, called a sea breeze.
• During Night time
• land cools faster than water.
• warmer air over the water rises and is replaced
  by the cooler, denser air from the land, creating
  an offshore wind called a land breeze.
• Demo http//www.youtube.com/watch?vxlqc3YJAmiQ
  featurerelated

23
Misconception 4All black objects are good
insulators.

• Radiant energy travels through empty space.
• For a black coloured object to become an
  insulator of thermal energy it as to be left out
  side in direct view of sunlight or near a roaring
  flame but not touching the flame.
• A black coloured object left under room
  temperature conditions will not turn into an
  insulator of thermal energy.
• Ex A plastic bottle filled with warm water and
  wrapped in black cloth will not be a good
  insulator of thermal energy.

24
Experiment Not all black objects are insulators

• Part A students make data tables to record the
  time and temperature.
• Fill 3 pie pans to the same level, one with dark
  soil, one with light sand, and one with water.
• Place the pie pans under a table lamp
• Place a thermometer into each pie pan.
• measures the temperature just under the surface
  of the substance .
• Record the starting temperatures on the data
  table.
• Turn on the lamp and record the temperature of
  each substance every minute for ten minutes.
• At the end of ten minutes, turn the lamp off.
• Part B Repeat the entire procedure but remove the
  lamp. Discuss the variations in the results.

25
Day 5 Managing the transfer of thermal energy

• Divide the class into groups of 5 and ask the
  students to implement drama in science and create
  a Talbot on the concepts learned.
• The students can also create a story by each
  person saying a sentence based on the prior
  knowledge of the concepts.
• Students can work in pairs and play Show it in
  action. Student A will start with a short
  sentence based on the concept. Student B will
  show the action for it and say another sentence.
  Student A will do that action and so on.
• Talk about methods used to control the transfer
  of thermal energy.
• Design challenge is introduced Building a
  thermos using a 2L pop bottle which will keep
  water above 75 degrees for two hours.

26
Societal issues that can be discussed in class

• Relate concepts to the function of steam engines.
• Dangers of rising sea levels due to global
  warming.
• Uses of some plastics as thermal energy
  conductors in the electronics industry.
• Discuss how convection can be used to explain the
  process of releasing smoke through a chimney.
• Formation of igneous rock .
• Theory behind using certain coloured clothing in
  countries that receive high amounts of sunlight.
• The purpose of using certain materials by fire
  fighters when fighting extreme fires.
• Annotated References.

27
Refer to the handout

• Placement of the concept within the unit.
• Place in the Curriculum.
• Advance preparations/ materials.
• Assessment (A) Evaluation (E).
• Learning styles (LS) / Multiple intelligence
  (MI).
• Differentiated Instruction.

28
Safety considerations

• Show knowledge necessary to use the materials,
  and tools involved in experiments.
• The skills needed to perform tasks efficiently
  and safely.
• Maintain a well organized and uncluttered work
  space.
• Follow established safety procedures.
• Identify possible safety concerns.
• Carefully follow the instructions and example of
  the teacher,
• Consistently show care and concern for their
  safety and that of others.
• Use fire safety procedures when using candles.
• Wear safety goggles at all time.

29
Thank You

• Special thank you to my mentor Roberta. Thank you
  for giving me constructive feedback and helping
  me set up the demonstrations.