Station 2: Refraction of Sound Waves Questions:
A. Content Standards The learner demonstrates understanding of heat and temperature, and the effects of heat on the body
2. Learner's Materials Pages 43-44
Teaching Date and
Time Quarter First (Physics)
DAY:
I. OBJECTIVES
A. Content Standards
The learner demonstrates understanding of heat and temperature and the effects of heat on the body.
B. Performance Standards C.
Learning Competencies / Objectives Write the LC code for each
(S8FE-Ig-29)
Differentiate between heat and temperature at the molecular level.
Objectives:
1. Define thermal expansion
2 .Determine experimentally how temperature affects thermal expansion of some objects.
II. CONTENT Module V: HEAT
Lesson 26: THERMAL EXPANSION
III. LEARNING RESOURCES
A. References
1. Teacher's Guide Pages 31
2. Learner's Materials Pages 43-44
3. Textbook Pages
4. Additional Materials from Learning
Resource (LR) portal
B. Other Learning Resource
IV. PROCEDURES
A. Reviewing previous lesson or presenting the
new lesson How is temperature related to the kinetic energy of particles?
B. Establishing a purpose for the Lesson
You are very familiar to a device called thermometer. You have most probably used this device many times. The one commonly available in our school laboratory is the liquid thermometer.
C. Presenting examples / instances of the new lesson
Why does the liquid inside the tube of the thermometer go up and down? Does the working principle of the mercury/alcohol thermometer also true to most solids?
D. Discussing new concepts and practicing new skills #1
Activity-see Lesson Guide pp 103-104
E.
Discussing new concepts and practicing new skills #2
Analysis:
1. What happens to the height of the weight when the wire is heated?
2. What factors affect the expansion of the wire?
3. Identify the effects of thermal expansion and contraction to some materials.
F. Developing mastery
(Leads to Formative Assessment 3) Discuss the answers in the activity given
G Finding practical applications of concepts and skills in daily living
There are some applications of thermal expansion in day-to-day life. Some of them are the following, or you may watch this short video www.youtube.com/watch?v=4UE_cxd7TEw for some practical application of thermal expansion used at home.
Possible answers:
What are the Engineering Applications of Thermal expansions?
1. Railway track:
Railway tracks are an example where the concept of thermal expansion is used. Space is left between railway tracks as an allowance for their expansion when temperature increases, otherwise the rails may buckle.
2. Steel Bridges:
Similarly, long steel bridges are designed to include expansion joints to allow for their expansion, by fixing one end and resting other end on rollers.
3. Mercury Thermometers:
Thermal expansion is applied in mercury that contains liquid, the volume of which changes as the temperature varies. Liquid occupy less space when cold, but additional space is needed when temperature varies. As the liquid expands, its volume changes and it is forced to flow along the tube that is calibrated to show the temperature.
(Note: Mercury thermometer is now being banned to be used in science laboratory because of its health hazards.)
4. Bi-metal strip Thermometers:
Bi-metal strips in a mechanical thermometer possess co-efficient of thermal expansion, due to which their expansion with a rise in temperature is different. The strips sin bend since the expansion or contraction of the material used is not similar. This concept is used in measurement of temperature.
5. Automobile Engine Coolant:
The concept of thermal expansion is also used in systems of engine coolant in automobiles. If coolant is filled in the radiator with engine in a cold condition, it will spill over with the heating of engine during operation. Thus an overflow tank is fitted that accumulates such coolant during thermal expansion, and as engine is cooled, it returns to the radiator.
H. Making generalizations and abstractions about the lesson
Thermal expansion is another effect of heat transfer. It does not apply only to the liquid inside the thermometer. In fact, it applies to almost everything around us, be it a solid, a liquid, or a gas.
What is thermal expansion and how does it work?
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature, through heat transfer. Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, the kinetic energy of its molecules increases.
What must happen to the temperature of a material for thermal expansion to occur?
Factors affecting thermal expansion. Imagine that a long, thin metal wire is heated. The wire expands. The amount by which it expands depends on three factors: its original length, the temperature change, and the thermal (heat) properties of the metal itself.
I. Evaluating Learning
Direction: Read each question carefully. Then select the letter of the correct answer.
1. A person cannot unscrew the lid of a pot of jam. He finds that the lid can be unscrewed after it has been held under hot water for a few seconds. Why he has to do this?
A. The air pressure in the jar falls B. The jam melts
C. The lid expands D. The glass expands.
2. The change in length of an object when it undergoes a temperature change is related to
A. its mass
B. its original length.
C. the magnitude of the temperature change.
D. both B and C
3. The change in length of an object subjected to a change in temperature
4. The working of a simple thermostat depends on A. thermal expansion.
B. specific heats.
C. the second law of thermodynamics.
D. condensation
5. An axle is too large to fit into the hole in a wheel that is made of the same metal. How can the axle be made to fit into the hole.
A. by heating the wheel alone
B. by cooling both the axle and the wheel C. by cooling the axle alone
D. by heating both the axle and the wheel J. Additional activities for application or
remediation
What is the effect of temperature change on phase changes?
V. REMARKS
VI. REFLECTION
A. No. of learners who earned 80% in the evaluation
B. No. of learners who require additional activities
for remediation who scored below 80%
C. Did the remedial lessons work? No. of learners who have caught up with the lesson
D. No. of learners who continue to require
remediation
E. Which of my teaching strategies worked well?
Why did these worked?
F. What difficulties did I encounter which my
principal or supervisor can help me solve?
G. What innovation or localized materials did I Use or discover which I wish to share with other teachers?
GRADES 1 to 12 School Grade Level Grade 8
Daily Lesson Log Teacher Learning Area SCIENCE
Teaching Date and
Time Quarter First (Physics)
DAY:
I. OBJECTIVES
A. Content Standards The learner demonstrates understanding of heat and