Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 2nd Term
Week: 2
Age: 15 years
Duration: 45 minutes
Subject: Food and Nutrition
Curriculum Theme: Food and Nutrition
Previous Lesson: Structure of the Digestive System.
Topic: Digestive system
Subject Matter: Functions of enzymes such as ptyalin (salivary amylase) and pepsin, role of water in digestion, role of water in absorption.

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define enzymes.
State the functions of ptyalin (salivary amylase) and pepsin.
Explain the role of water in the digestion process.
Describe how water aids in the absorption of digested food.

Affective Domain:

Appreciate the importance of enzymes in breaking down food.
Recognise the significance of water for healthy digestion and absorption.
Show interest in learning about the body’s digestive processes.

Psychomotor Domain:

Identify the sites of action for ptyalin and pepsin on a digestive system chart.
Outline the steps where water is involved in digestion and absorption.

Participate actively in class discussions about the digestive system.
Collaborate with peers to answer questions related to enzyme function.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Food and Nutrition.
State Unified Scheme of Work for Senior Secondary Schools.
Food and Nutrition for Senior Secondary Schools by C.B. Olusanya.

Instructional Materials

The teacher will teach this lesson with the aid of:

A chart showing the summary of the digestive process.
Textbooks on Food and Nutrition.
Marker and whiteboard/chalkboard.

Rationale for the Lesson

This lesson helps pupils understand how the body breaks down food into usable forms and absorbs nutrients. Knowing the roles of enzymes and water is important for appreciating the body’s functions and making informed choices about nutrition and hydration for good health.

Prerequisite/Previous Knowledge

Pupils should have prior knowledge of the main organs of the digestive system and the basic food nutrients.

Lesson Content/Board Summary

Digestive System: Functions of Enzymes and Role of Water

Enzymes in Digestion

Enzymes are biological catalysts, which are protein molecules that speed up biochemical reactions in the body without being used up themselves. They are specific in their action, meaning each enzyme acts on a particular type of food.

The following are important enzymes and their functions:

Ptyalin (Salivary Amylase): Found in saliva (mouth). It acts on cooked starch, breaking it down into maltose (a simpler sugar).
Pepsin: Found in gastric juice (stomach). It acts on proteins, breaking them down into peptides (smaller protein units). Pepsin works best in an acidic environment.
Amylase (Pancreatic Amylase): Found in pancreatic juice (small intestine). It continues the breakdown of starch into maltose.

Role of Water in Digestion

Water is essential for the digestive process in several ways:

It moistens food in the mouth, making it easier to chew and swallow.
It helps in the formation of saliva and other digestive juices.
It acts as a solvent, allowing enzymes to dissolve and function effectively.
It helps in the movement of food through the digestive tract (peristalsis).
It lubricates the digestive tract, preventing constipation.

Role of Water in Absorption

Water also plays a significant role in the absorption of nutrients:

It serves as the medium through which digested nutrients (like glucose, amino acids, vitamins, and minerals) are dissolved and transported across the intestinal walls into the bloodstream.
It helps maintain the appropriate concentration gradient for nutrient absorption.
It is absorbed itself, along with electrolytes, mainly in the large intestine.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and reviews the previous lesson on the structure of the digestive system. The teacher asks pupils to recall what happens to food after it enters the mouth.
Pupils’ Activity: Pupils respond by mentioning chewing and swallowing. They recall the organs of the digestive system.
Learning Point: Pupils connect new learning to previous knowledge about the digestive system.

Step 2: Presentation of Topic

Time: 5 minutes
Teaching Skill: Explanation/Introduction
Teacher’s Activity: The teacher introduces the topic “Digestive System: Functions of Enzymes and Role of Water” and writes it on the board. The teacher explains that today’s lesson will focus on how food is chemically broken down and the role of water.
Pupils’ Activity: Pupils listen attentively and copy the topic into their notebooks.
Learning Point: Pupils are aware of the lesson’s focus.

Step 3: Explanation of Enzymes and their Functions

Time: 10 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines enzymes and explains their general characteristics. Using the digestive system chart, the teacher points out the locations where ptyalin (salivary amylase) and pepsin act, explaining their specific functions in breaking down starch and protein respectively. The teacher also mentions pancreatic amylase.
Pupils’ Activity: Pupils listen, observe the chart, ask questions for clarification, and take notes.
Learning Point: Pupils understand what enzymes are and the specific roles of ptyalin, pepsin, and amylase.

Step 4: Discussion on Role of Water in Digestion

Time: 8 minutes
Teaching Skill: Discussion/Questioning
Teacher’s Activity: The teacher leads a discussion on the various ways water assists in the digestion process. The teacher asks questions like, “What happens if you try to swallow very dry food?” to prompt pupils’ understanding.
Pupils’ Activity: Pupils contribute to the discussion by sharing their ideas and noting the points discussed.
Learning Point: Pupils comprehend the importance of water in facilitating digestion.

Step 5: Explanation of Role of Water in Absorption

Time: 7 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains how water is crucial for the absorption of digested nutrients from the small intestine into the bloodstream. The teacher emphasizes water as a transport medium.
Pupils’ Activity: Pupils listen and take down notes on the role of water in absorption.
Learning Point: Pupils understand water’s function in nutrient absorption.

Step 6: Class Activity/Review

Time: 5 minutes
Teaching Skill: Collaborative Learning
Teacher’s Activity: The teacher divides pupils into small groups and asks them to briefly discuss two ways enzymes and water are important for the digestive system.
Pupils’ Activity: Pupils discuss in groups and a representative from each group shares their points with the class.
Learning Point: Pupils reinforce their understanding through peer discussion and verbalisation.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define enzymes.
State the function of ptyalin (salivary amylase) and pepsin.
Mention three ways water helps in the digestion of food.
Explain how water aids in the absorption of digested nutrients.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the importance of enzymes and water in the digestive and absorptive processes. The teacher assigns homework: “List five foods that are rich in protein and explain how pepsin acts on them.”
Pupils’ Activity: Pupils listen to the summary and copy the homework into their notebooks.
Learning Point: Pupils consolidate their learning and apply knowledge to new scenarios.

Lesson Keywords

Enzymes – Biological catalysts that speed up chemical reactions in the body.
Ptyalin (Salivary Amylase) – An enzyme in saliva that breaks down starch into maltose.
Pepsin – An enzyme in gastric juice that breaks down proteins into peptides.
Digestion – The process of breaking down food into smaller molecules that can be absorbed.
Absorption – The process by which digested food molecules pass into the bloodstream.

Differentiation

For pupils who grasp concepts quickly, the teacher can ask them to research other digestive enzymes and their functions. For pupils needing more support, the teacher will provide simplified definitions and visual aids, ensuring they understand the basic functions of ptyalin, pepsin, and water.

Note for teachers using this lesson plan

Encourage pupils to relate the concepts of enzymes and water to their daily eating habits and overall health. Emphasize that proper hydration is essential for efficient digestion. Ensure the digestive system chart is clear and easily visible to all pupils.