TERM: 3RD TERM
WEEK: 2
CLASS: Junior Secondary School 2
AGE: 13 years
DURATION: 40 minutes each for 2 periods
DATE:
SUBJECT: Basic Science
TOPIC: Thermal energy II
SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to
1.) List and describe three methods of heat transfer.
2.) State real life applications of heat conduction
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source
INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 2
INSTRUCTIONAL PROCEDURES: PERIOD 1-2:
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PRESENTATION
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TEACHER’S ACTIVITY
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PUPIL’S ACTIVITY
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STEP 1
Review
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The teacher revises the previous lesson.
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Learners pay attention
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STEP 2
Introduction
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He lists and describes the three methods of heat transfer
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Learners pay attention and participate
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STEP 3
Explanation
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He states real life applications of heat conduction
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Learners pay attention and participate
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STEP 4
NOTE TAKING
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The teacher writes a short note on the board for the learners to copy
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The learners copy the note from the board
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NOTE
THERMAL ENERGY
Methods of Heat Transfer
a) Conduction:
- Conduction is the transfer of heat through a substance without the movement of the substance itself. It occurs when particles in a material collide and transfer energy to neighboring particles. This happens primarily in solids.
- Example: When a metal spoon is placed in a hot cup of tea, the heat from the tea travels through the spoon's metal, warming the other end.
b) Convection:
- Convection is the transfer of heat through fluids (liquids or gases) due to the movement of the fluid itself. As the fluid is heated, it becomes less dense and rises, while cooler fluid moves in to replace it, creating a continuous circulation pattern.
- Example: In a pot of boiling water, hot water rises, and cooler water sinks, creating a convection current.
c) Radiation:
- Radiation is the transfer of heat in the form of electromagnetic waves, such as infrared radiation. It does not require a medium (solid, liquid, or gas) to travel through, so it can occur in a vacuum.
- Example: The heat we feel from the sun is a result of radiation. Similarly, a fire emits heat through radiation, warming the surrounding area.
Real-Life Applications of Heat Conduction
a) Cooking (e.g., pots and pans):
- When cooking, the heat from the stove is conducted through the metal of the pot or pan to the food inside. The metal transfers the heat to the food, allowing it to cook.
b) Heat Transfer in Buildings (e.g., Insulation):
- In buildings, conduction plays a role in the heat exchange between the inside and outside environments. Insulation materials are used to reduce heat conduction and maintain indoor temperatures, keeping heat inside during winter and outside during summer.
c) Cooling Systems (e.g., Refrigerators and Air Conditioners):
- In a refrigerator, heat is conducted from the warm interior to the coils on the back of the unit. The heat is then removed from the coils and dissipated into the air.
d) Electronics (e.g., Heat Sinks):
- Heat sinks in electronics, such as computer processors, use conduction to transfer heat away from the device. The heat is conducted away from sensitive components to prevent overheating.
e) Warming Blankets:
- In electric heating blankets, heat is conducted through the fabric to warm the body of the user
EVALUATION:
- What is conduction, and how does it occur in solids? Provide an example.
- Explain how convection works in liquids and gases. How does this method of heat transfer differ from conduction?
- Describe the process of radiation. Why does it not require a medium to transfer heat?
- How is heat conduction used in everyday life? Mention at least two examples and explain their significance.
- What factors can affect the rate of heat conduction in materials? How can the efficiency of heat conduction be improved in various applications?
CLASSWORK: As in evaluation
CONCLUSION: The teacher marks their books and commends them positively
