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Subject: Biology
Semester: 2
Period: 4
Week: 19
School Name:
Teacher’s Name:
Subject: Biology
Grade Level: Grade 12
Date: Week 19
Lesson Duration: 45 minutes
Week & Period: Week 19, Period IV
Topic: Excretory System
Sub-topic: Organs of the Excretory System and their Functions
Learning Objectives
By the end of this lesson, learners should be able to:
- Describe the organs involved in excretion in humans.
- State the functions of each excretory organ.
- Explain the concept of homeostasis as it relates to the excretory system.
- Relate the role of the excretory system to waste removal and internal balance.
Previous Knowledge
Learners already understand the basic functions of human body systems including the digestive and circulatory systems.
Instructional Materials
- Charts of the human excretory system
- Model of kidney and urinary system
- Labeled diagrams (skin, lungs, large intestine, liver)
- Flashcards for organ names and functions
- Short animations or videos of kidney function
Lesson Development – ABC Model
A – Anticipation (Warm-up Activity)
Time: 5–7 minutes
Ask learners:
- What happens to the food and drinks we consume after digestion?
- What waste products does the body eliminate every day?
Use the discussion to introduce the term excretion and list the main organs on the board.
B – Building Knowledge (Main Lesson)
Time: 25–30 minutes
Explanation of Excretory Organs and Functions:
- Kidneys – filter blood to remove urea and excess salts and water as urine.
- Ureters – tubes that carry urine from kidneys to the bladder.
- Urinary bladder – stores urine.
- Urethra – tube through which urine exits the body.
- Skin – excretes water, salt, and small amounts of urea through sweat.
- Liver – breaks down excess amino acids and toxins.
- Lungs – excrete carbon dioxide and water vapor.
- Large intestine – removes solid waste (though not excretion in the strict sense, included for clarity).
Introduce Homeostasis:
- The ability of the body to maintain a stable internal environment (e.g., water balance and salt concentration).
- Highlight how kidneys regulate this.
Learners’ Activities
- Label blank diagrams of the excretory organs.
- In pairs, match excretory organs with their waste products.
- Group discussion: How does each organ contribute to keeping the body "clean"?
C – Consolidation (Conclusion & Assessment)
Time: 8–10 minutes
- Quick review questions:
- Which organ is responsible for filtering blood?
- What waste product is removed by the lungs?
- What does the liver convert excess amino acids into?
- Oral quiz using flashcards.
- Written homework: Fill in the blanks and match organ to function (worksheet).
Short Notes (Summarized Recap)
- Excretion is the removal of metabolic waste from the body.
- Kidneys remove urea and excess water.
- Lungs remove carbon dioxide and water vapor.
- Skin removes salts and water through sweat.
- Liver helps in detoxification and urea formation.
- Homeostasis helps the body maintain balance, especially in water and salt levels.
Extra Instructions for Expanded Work
Expanded Notes:
- Provide a labeled handout summarizing the role and structure of each organ.
- Include a simple diagram showing the flow of urine from kidneys to urethra.
Assignment:
- Learners should write a short paragraph on how the kidney contributes to homeostasis.
- Identify which diseases can affect the excretory system and how they impact its function (e.g., kidney failure, liver cirrhosis).
Optional Extension:
- Watch a 5-minute educational clip about dialysis and write two things learned.
Differentiation / Inclusive Strategies
- Diagrams and flashcards for visual learners.
- Hands-on labeling for kinesthetic learners.
- Group discussion and oral explanations for auditory learners.
- Allow learners with literacy challenges to express understanding through drawing or speaking.
Teacher Reflection
- Did learners correctly name and explain the organs of the excretory system?
- Were they able to connect each organ to its role in waste elimination?
- Was homeostasis clearly understood?