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Subject: Biology
Semester: 2
Period: 4
Week: 20
School Name:
Teacher’s Name:
Subject: Biology
Grade Level: Grade 12
Date: Week 20
Lesson Duration: 45 minutes
Week & Period: Week 20, Period IV
Topic: Respiratory System
Sub-topic: Organs of the Respiratory System and Their Functions
Learning Objectives
By the end of this lesson, learners should be able to:
- Identify the organs of the human respiratory system.
- Describe the structure and function of each organ in respiration.
- Explain the processes of internal and external respiration.
- Recognize the importance of breathing and gaseous exchange.
Previous Knowledge
Learners have previously learned about the circulatory system and how oxygen is transported in the blood.
Instructional Materials
- Diagram of the respiratory system
- Chart showing alveoli and gaseous exchange
- Flashcards with organ names and functions
- Model of lungs
- Real-life examples: balloon to simulate lung expansion
Lesson Development – ABC Model
A – Anticipation (Warm-up Activity)
Time: 5–7 minutes
Ask: “Why do we breathe?”
Let learners touch their chest and observe the movement as they inhale and exhale. Ask: “Where does the air go?”
Use this to introduce the respiratory system.
B – Building Knowledge (Main Lesson)
Time: 25–30 minutes
Key Respiratory Organs and Functions:
- Nose/Nasal cavity – filters, warms, and moistens air.
- Pharynx – passageway for air and food.
- Larynx (voice box) – produces sound, protects trachea.
- Trachea (windpipe) – air passage to the bronchi.
- Bronchi and bronchioles – branch into lungs to carry air.
- Lungs – main respiratory organs.
- Alveoli – tiny sacs where gaseous exchange occurs.
- Diaphragm – muscular sheet controlling breathing.
Process of Breathing:
- Inspiration: diaphragm contracts, air enters lungs.
- Expiration: diaphragm relaxes, air exits lungs.
Gaseous Exchange:
- Oxygen from air enters blood through alveoli.
- Carbon dioxide from blood enters alveoli to be exhaled.
Learners’ Activities
- Draw and label the human respiratory system.
- Group role-play of air flow from nose to alveoli.
- Balloon activity to simulate inhalation/exhalation.
- Pair discussion: What would happen if the alveoli were damaged?
C – Consolidation (Conclusion & Assessment)
Time: 8–10 minutes
- Review Questions:
- What is the role of the diaphragm in breathing?
- Where does gaseous exchange take place?
- List two differences between inhalation and exhalation.
- Quick worksheet: Match organ to function.
- Homework: Create a labeled drawing of the respiratory system and describe how oxygen gets into the blood.
Short Notes (Summarized Recap)
- The respiratory system allows us to breathe in oxygen and breathe out carbon dioxide.
- Main organs: nose, pharynx, larynx, trachea, bronchi, lungs, alveoli, and diaphragm.
- Inhalation brings in air; exhalation pushes it out.
- Gaseous exchange happens in the alveoli. Oxygen goes into blood; carbon dioxide comes out.
Extra Instructions for Expanded Work
Expanded Notes:
- Provide a labeled handout with organ descriptions.
- Include explanation of external vs internal respiration.
Assignment:
- Write a paragraph comparing the roles of lungs and kidneys in keeping the body healthy.
- Optional: Interview a nurse or adult about respiratory diseases and write a report.
Differentiation / Inclusive Strategies
- Use models and diagrams for visual learners.
- Provide drawing tasks for kinesthetic learners.
- Use oral discussion and Q&A for auditory learners.
- Provide extra support sheets for struggling learners.
Teacher Reflection
- Did learners correctly identify and describe each part of the respiratory system?
- Were they able to trace the flow of air through the system?
- Was gaseous exchange clearly understood?