Biology
I. OBJECTIVES:
At the end of the lesson, 80% of the students are expected to:
1. identify the parts of the digestive system,
2. describe the coordinating functions of the organs of the digestive system,
3. trace the pathway of food as it is being digested and;
4. give importance to the healthful practices that affects the digestive system.
II. SUBJECT MATTER:
UNIT: IV- Living things and their environment
Module-3 The Digestive System
TOPIC: The Digestive System: Its Parts and Functions
A. Science Concepts:
Food plays a central role in the survival of the species. They give energy that enables us
to carry out all the activities for each day.
We obtain energy from the food that we eat through the process called digestion.
Digestion means the process of breaking down of food from bigger molecules to smaller
one.
Digestion of food is carried out by organs and substances of the digestive system.
Digestion starts from the mouth by a process called ingestion, where food is chewed
and broken down to smaller pieces for easier digestion. This is called mechanical
digestion.
Initial chemical digestion also starts from the mouth. This is carried by the enzymes.
Enzymes are molecule that speeds up the chemical reaction. Enzyme present in the
saliva called amylase helps breakdown carbohydrates.
After swallowing, the food enters to esophagus and move down into stomach. The
process is called peristalsis.
In the stomach, the pieces of food combined with gastric juices and acids. Enzymes such
protease and lipase help break down proteins in the stomach and fats in the small
intestine respectively.
Digestion in the small intestine is very important because this is where nutrients are
absorbed in the villi and enter the circulatory system.
Wastes that remain after digestion will go the large intestine where water is also
reabsorbed. These wastes including the water are temporarily stored in the rectum
before they are excreted out of the body through the anus.
B. Processes/Skills:
Identifying, describing, tracing the path of food and explaining the process involve in
digestion.
C. Value focus:
Giving importance to the healthful practices that affects the digestive system.
D. References: Grade VIII Science Learner’s Module page 291-305
E. Materials:
LCD Projector and screen, laptop, manila paper, masking tape, illustration of the digestive system.
III. DEVELOPMENTAL ACTIVITIES
Teacher’s activity Student’s activity
A. Pre-Activity
a. Prayer The teacher will ask somebody to Students will stand and pray.
lead the prayer
b. Review of the 1. What is the basic structural unit of Cells
previous lesson life?
2. Can you name some types of cells Skin cells, blood cells, brain
in your body? cells, sperm cells, egg cells…
3. How do cells carry their functions? By using energy
4. how can cells obtain energy? By eating foods.
c. Motivation
(the teacher will post a picture of
a various foods in the projector)
Seeing the picture, what comes Student’s answer may vary.
into your mind?
Are you hungry? Yes ma’am…
Why do you think you feel Because of the foods.
hungry?
So, what particular part of our Stomach...
body do we need to satisfy when
we are hungry?
What do you think is the system Digestive system
responsible for the food we eat?
B. Activity proper:
1. Grouping and Giving of
Activity Cards/Sheets (The teacher will divide the class
into 3 groups.)
The teacher will prepare Group leaders will get one
envelopes containing instructions envelop for their activity.
and materials for students’
activities.
2. Perform the Activity by The teacher will supervise the The students will do their
Group students. activity.
GROUP 1
Instructions:
1. Identify the name of each
part of the digestive
system in the illustration
provided.
2. Describe each functions of
the parts. Paste the
description of functions
beside each part.
3. Paste your output on the
board after 5 minutes.
4. Choose a presenter/
reporter to present your
output.
GROUP 2
Instructions:
1. Make a simple illustration
tracing the pathway of
food as it is being digested
in the digestive system.
2. Draw an arrow to connect
the organs.
3. Paste your output on the
board after 5 minutes.
4. Choose a presenter/
reporter to present your
output.
GROUP 3
Instructions:
1. Make a healthy food
pyramid.
2. In your pyramid, write all
healthy foods that you
know that can provide
you with tons of vitamins
and minerals to keep your
digestive tract healthy.
3. Kindly explain your
illustration and the
importance of these food
in keeping our digestive
system healthy. Write
your answer below the
pyramid.
4. Paste your output on the
board after 5 minutes.
5. Choose a presenter/
reporter to present your
output.
C. Post Activity The teacher will let the students Students will present their
1. Presentation of the to present their output. outputs.
activity
The teacher will show the correct
2. Checking of the output answer.
1. How do we obtain energy from We can obtain energy from
C. Lesson Proper the food that we eat? the food that we eat through
digestion.
2. What do we mean by digestion? The process of breaking
down food by mechanical
and enzymatic action in the
alimentary canal into
substances that can be used
by the body.
3. What are examples of organism Humans, pigs, etc…
having a complete digestive
system?
4. What are the different organs that Mouth, esophagus, stomach,
we can see in human digestive small intestine, large
system? intestine, rectum, anus, liver,
gall bladder and pancreas
5. What are the functions of these Students will answer based
different organs? on what they have
understood from the
PowerPoint presented to
them.
6. What is saliva? Saliva is a watery liquid
made by the salivary gland.
it softens and wets the food
in the mouth and also initially
starts the chemical digestion
through enzyme present in
it.
7. What do we mean by enzyme? Enzyme are the molecules
that speed up chemical
reactions.
it serves as catalyst in the
digestion process.
enzyme present in the saliva
is called amylase.
8. What is the function of amylase?
Amylase is an enzyme
present in the saliva that
helps digest carbohydrates.
9. What do we mean by Peristalsis?
Peristalsis is the process by
which the muscle of the
esophagus contract, allowing
the bulos to move down the
stomach
10. What will happen to the particles
The undigested particles of
of food which are not absorbed by
the food or those that were
our cells?
not absorbed by the cells will
go to the large intestine
where water is also
reabsorbed.
These waste including the
water that was not
reabsorbed are temporarily
stored in the rectum before
they are excreted out of the
body through the anus.
So, as a summary, the processes involved
in digestion are:
1. Ingestion
2. digestion
3. absorption
4. excretion
Basing on the topic that we have
discussed, what general idea have you
learned?
Guide questions: We learned that:
D. Generalization:
1. How do we obtain nutrients from the We can obtain energy from
food that we eat? the food that we eat through
digestion.
Digestion is the process of
2. What do we mean by digestion?
breaking down food by
mechanical and enzymatic
action in the alimentary canal
into substances that can be
used by the body.
3. What are the pathways of food as it is
From the mouth going to the
being digested?
esophagus, to the stomach.
The small intestine absorbs
the nutrients through its villi
and will carry by the blood
stream throughout the body.
The waste products that do
not absorbed by the cells will
pass through the large
intestine and will be
deposited in the rectum. And
later, it will be excreted out
through the anus.
We call it peristalsis.
4. What do we call that process wherein
the food is moving from esophagus down
to the stomach?
5. What will happen to the waste The waste that remains
materials that are not absorbed by the during digestion, will pass
cells of our body? through the large intestine,
and temporarily stored in the
rectum, and later will be
excreted out by the anus.
1. How can we make our digestive tract By eating low-fat and high-
E. Valuing healthy? Cite an examples on how to take fiber foods, and avoidance of
care our digestive system. processed and fried foods.
Incorporating greens, fruits,
and vegetables each day will
help to maintain the
homeostasis of our digestive
system.
IV. EVALUATION:
Test I- Draw a simple illustration tracing the pathway of food as it is being digested in the digestive
system. You can draw an arrow to connect the organs.
Test II. Essay
1. Explain the importance of the parts of the digestive system.
2. Explain briefly how do nutrients from the food absorbed by the cells of our body?
3. Cite an example on how to take care of our digestive system.
V. ASSIGNMENT:
Make a simple meal plan for a week that depicts a healthy lifestyle in your assignment
notebook.
PREPARED BY:
Alleen Joy B. Solivio
Science Teacher
INSTRUCTIONS:
6. Make a healthy food pyramid.
7. In your pyramid, write all healthy foods that you know that can provide you with tons of
vitamins and minerals to keep your digestive tract healthy.
8. Kindly explain your illustration and the importance of these food in keeping our digestive
system healthy. Write your answer below the pyramid.
9. Paste your output on the board after 5 minutes.
10. Choose a presenter/ reporter to present your output.
Sample:
Answer: ________________________
INSTRUCTIONS:
5. Identify the name of each part of the digestive system in the illustration provided.
6. Describe each functions of the parts. Paste the description of functions beside each part.
7. Paste your output on the board after 5 minutes.
8. Choose a presenter/ reporter to present your output.
INSTRUCTIONS:
5. Make a simple illustration tracing the pathway of food as it is being digested in the digestive
system.
6. Draw an arrow to connect the organs.
7. Paste your output on the board after 5 minutes.
8. Choose a presenter/ reporter to present your output.
