Key Stage 3 Science
“Food and Digestion Unit”
“Food and Digestion Unit”
From KS2:
Statement
Sc2 1a
Sc2 2a
Sc2 2b
Sc2 2c
Description
That the life processes common to humans and other animals include
nutrition, movement, growth and reproduction.
About the functions and care of teeth.
Food for activity and growth, and the importance of an adequate and
varied diet for health.
That the heart acts as a pump to circulate the blood through vessels
around the body, including through the lungs.
Unit Overview:
Establish prior learning:
o
o
The seven life processes
Human organs
o
Consider how organs work together
forming organ systems.
Explain the functions of different organ
systems.
Focus on digestive system – structure
and function.
o
o
o
Consider the components of a healthy
diet and what these components are used
for.
o
Explain where the different components
are digested, using knowledge of
enzymes.
‘Food and Digestion’ [LESSON 1]
Big Question: Could a human live without a stomach?
Science content
State the names and
locations of the main human
organs.
Explain how these organs
work together to enable
humans to carry out the
seven life processes.
Lesson Objectives
Science skills
Transferable skills
Collaborate with others to
work towards common goals
(PLTS).
Work with others (SEAL).
Key Words
Brain; Breathing System; Circulatory System; Digestive System; Excretory System;
Heart; Intestine; Kidneys; Liver; Lungs; Nervous System; Organ; Organ System;
Stomach
Resources:
Laminated posters of human torso with laminated organs and labels.
Blue tack.
Human torso model.
Worksheets – Human Body outline and Human Organs to stick onto outline.
Organ Systems Wordsearch.
Scissors, glue and colouring pencils.
Lesson Plan
STARTER
1. Students work in groups to stick organs and labels in the correct positions on the
human torso. Observe students to assess prior learning. [5 mins]
2. Discuss names and locations of organs, using human torso model to show 3D version
of organs. [5 mins]
MAIN
1. Using worksheets (‘Human Body’ and ‘Human Organs’), students work individually to
cut out organs and stick in the correct place on the human body and label. [15 mins]
2. Ask students for the names of the seven life processes (MRS GREN/NERG). Ask
students which organs enable the human body to carry out the process of ‘nutrition’.
Students colour the organs on their worksheet that carry out ‘nutrition’ in the same
colour. Tell students to discuss in pairs which organs they think are needed for the
processes of ‘respiration’ and ‘excretion’. Take feedback and tell students to colour
organs appropriately. [15 mins]
3. Introduce the term ‘organ system’ and ask students if they know the name of the
system that carries out the process of ‘nutrition’. Add a key to worksheet to show
which organs are parts of each system. [10 mins]
PLENARY
1. Students complete worksheet ‘Organ systems wordsearch’. [10 mins]
Assessment Opportunities
Observing students during starter activity.
Listening to and responding to ideas during discussions.
Notes
‘Food and Digestion’ [LESSON 2]
Big Question: Could a human live without a stomach?
Lesson Objectives
Science content
Science skills
State which organs make up Use an existing model or
the digestive system and
analogy to explain a
describe their functions.
phenomenon.
Transferable skills
Assess themselves and
others, identifying
opportunities and
achievements (PLTS).
Invite feedback and deal
positively with praise,
setbacks and criticism
(PLTs).
Give and receive feedback –
as individuals, class or group
(SEAL).
Key Words
Anus; Appendix; Gullet; Gut; Faeces; Large Intestine; Rectum; Small Intestine;
Stomach
Resources:
Worksheets – Comic Strip, The Digestive System.
Scissors and glue.
Laminated cards – Sequencing Digestion.
Food sample, equipment to model journey through digestive system (see teacher’s
instruction sheet – ‘Modelling the Digestive System’).
Lesson Plan
STARTER
1. Explain that we are now focusing on one organ system – The Digestive System.
2. Assess students’ current understanding of digestion. In pairs students complete a
comic strip to explain what they think happens during digestion. [10 mins]
MAIN
1. Ask some groups to explain their comic strips to the rest of the class. Ask the rest
of the class questions on each presentation, to which they can indicate whether they
agree with the ideas suggested by holding up green, orange or red cards. [10 mins]
2. Link the ideas discussed back to the organs identified last lesson - ask students
for the names of the main organs that make up the digestive system. Additional
organs that were not discussed in the previous lesson may need to be added. Write
the organ names on the board. [5 mins]
3. Give students worksheet ‘The Digestive System’. Students label the organs of the
digestive system and match organ names to functions. [10 mins]
4. Model the journey through the digestive system (see sheet ‘Modelling the
Digestive System’ for suggestion of how to do this) – ask for student volunteers to
help at various stages of the model. Question students throughout. [15 mins]
PLENARY
Give students sets of cards and ask them to sequence them to explain what happens
during digestion. [10 mins]
Assessment Opportunities
Listening and responding to ideas during discussions.
Observe students during card sort activity.
Notes
At this stage of the unit, students will not have covered the food groups, therefore
only refer to enzymes as helping to break food down. Enzymes will be covered in
detail later in the unit.
Comic Strip to Explain Digestion
Modelling the Digestive System
Equipment:
Plastic funnel
Long balloon, end cut off
Rubber glove, one finger cut off
30cm hose/rubber tube
One leg of a pair of tights
Large beaker
Tape and scissors
Clothes pegs
Spoon
Brown coloured cereal, milk, juice
Diagram:
Sequencing Digestion
Food goes into the mouth.
The teeth chew the food.
The food is mixed with
saliva.
When we swallow, the food
goes down the gullet to
the stomach.
In the stomach, the food
mixes with acid and
enzymes. The acid and
enzymes help to break
down the food.
The food leaves the
stomach and goes into the
small intestine. It is
mixed with more enzymes
to break it down even
more. Useful substances
from the food pass into
the blood.
Food that we cannot
digest goes from the small
intestine into the large
intestine. Here water
passes out of the
undigested food into the
blood.
Undigested food from the
large intestine is stored.
This solid waste passes
out of the anus.
The Digestive System
On the diagram below, write in the name of the organ that each line is pointing to. Use
these words:
rectum
small intestine
stomach
mouth
gullet
large intestine
Now cut out the boxes at the bottom of the page showing the functions of these organs.
Stick the correct box underneath the correct organ name.
Water is absorbed here.
More enzymes are added
here, to complete digestion.
The soluble food is
absorbed.
Faeces are stored here.
Takes food to the stomach.
Food is ground up here and
mixed with saliva.
The food is churned up with
strong acid here and
enzymes.
‘Food and Digestion’ [LESSON 3]
Big Question: What is in a slice of bread?
Science content
State the names of the
seven components of a
balanced diet and provide
examples of foods that are
good sources of starch and
sugar.
Explain how foods can be
tested for the presence of
starch and sugar.
Lesson Objectives
Science skills
Describe and record
observations
systematically.
Transferable skills
Support conclusions, using
evidence (PLTS).
Work with others, e.g. to
investigate, experiment
(SEAL).
Key Words
Balanced Diet; Benedict’s solution; Carbohydrate; Diet; Fat; Fibre; Iodine; Mineral;
Protein; Starch; Sugar; Vitamin; Water
Resources:
Questions and score grid for Healthy Eating Questionnaire.
Food samples.
Equipment for starch and sugar food tests.
Lesson Plan
STARTER
1. Ask students questions from the Healthy Eating Questionnaire. Students record
yes/no answers.
2. Read out score for each question, students calculate their total score.
3. Explain what scores mean. Ask students to give indication of score using red,
orange and green cards. [15 mins]
MAIN
1. Discuss certain questions from questionnaire and obtain names of food groups from
discussion. E.g. Ask students why they would not score well if they eat chocolate
every day – fat content; why they would score well if they eat fruit every day –
vitamin content. Write names of food groups on board. Students record in a table
with two columns – ‘food group’ and ‘good sources’. Leave ‘good sources’ column blank
to complete later. [10 mins]
2. Provide students with method for starch and sugar tests. Explain that they will
carry out tests to find out whether certain foods contain these carbohydrates. Ask
students to suggest what columns they will need in a results table. Draw table on
board for students to copy. [5 mins]
3. Students carry out food tests and record results. (Shorten practical if necessary
by giving each group of students a different food sample to test and pool results).
[20 mins]
PLENARY
1. Obtain feedback from students. Discuss whether results were as expected.
2. Fill in carbohydrate – starch and sugar – rows in table to show good sources of
these groups. Discuss other good sources. [10 mins]
Assessment Opportunities
Listening and responding to ideas during discussions.
Observing students during practical, questioning individuals/groups.
Notes
Healthy Eating Questionnaire
Questions
1. Do you usually eat breakfast?
2. Do you eat cereal for breakfast?
3. Do you have a drink before you come to school?
4. Do you eat any fruit at breaktime?
5. Do you eat crisps at breaktime?
6. Do you eat chocolate or sweets at breaktime?
7. Do you drink a fizzy drink at breaktime?
8. Do you usually eat chips for lunch?
9. Do you usually eat a cake or burger for lunch?
10. Do you usually eat some chocolate at lunchtime?
11. Do you usually eat a piece of fruit at lunchtime?
12. Do you eat sandwiches for lunch?
13. Do you eat brown/wholemeal bread?
14. Do you eat any fresh vegetables during the day?
15. Do you eat any fresh fruit during the day?
16. Do you eat some meat or cheese during the day?
17. Do you eat cakes every day?
18. Do you eat sweets every day?
19. Do you add extra salt to your food?
20. Do you drink some milk every day?
Score Grid
Start with a score of 25. Add or subtract points for each ‘yes’ reply,
following the grid below:
1
+1
2
+2
6
7
3
4
5
+1
+2
–1
8
9
10
–3
–1
–3
–1
–2
11
12
+2
+2
+1
16
17
13
14
15
+1
+3
+2
18
19
20
–2
–1
+1
–1
Scores:
10-20 You need to think about what you’re eating. To stay healthy you need to cut down on all that
fattening food and eat much more fresh fruit and vegetables.
20-30 Your diet is fairly well balanced but don’t be tempted by the fattening foods, even if they look
glamorous.
30-40 You are eating on the right lines to stay fit. Make sure you get enough of the right foods and
don’t be tempted to lose too much weight.
‘Food and Digestion’ [LESSON 4]
Big Question: What is in a slice of bread?
Science content
Provide examples of foods
that are good sources of
protein and fat.
Explain how foods can be
tested for the presence of
protein and fat.
Lesson Objectives
Science skills
Describe and record
observations
systematically.
Transferable skills
Support conclusions, using
evidence (PLTS).
Work with others, e.g. to
investigate, experiment
(SEAL).
Key Words
Balanced Diet; Biuret solution; Carbohydrate; Diet; Fat; Fibre; Mineral; Protein;
Starch; Sugar; Vitamin; Water
Resources:
Food samples.
Equipment for protein and fat tests.
Lesson Plan
STARTER
Write the key words below on the board and tell students that they are going to play
‘splat’. [10 mins]
Procedure
- Ask two volunteers to stand facing each other on either side of the words.
- Invite another student to define one of the key words without using it.
- The winner is the first volunteer to splat the correct key word with their hand.
- The winner should stay on and the student who defined the key word should replace
the other volunteer.
Key words: protein, fat, carbohydrate, vitamins, fibre, minerals, iodine, starch, sugar,
balanced diet.
MAIN
1. Recap the work from the previous lesson on testing for starch and sugar. Explain
that during today’s lesson students are going to test for fat and protein using the
same food samples as before. [5 mins]
2. Provide students with method for protein and fat tests. Ask students to design
their results table, using previous lesson’s work as a guide. [10 mins]
3. Students carry out food tests and record results. (Shorten practical if necessary
by giving each group of students a food sample to test and pool results). [20 mins]
PLENARY
1. Obtain feedback from students. Discuss whether results were as expected.
2. Fill in protein and fat rows in table to show good sources of these groups. Discuss
other good sources.
3. Discuss good sources of remaining food groups – fibre, water, vitamins and
minerals – and record in table. [15 mins]
Assessment Opportunities
Listening to and responding to ideas during discussions.
Observing students during practical, questioning individuals/groups.
Homework
Tell students to collect the labels from seven foods – each one high in at least one of
the seven nutrients needed by the body. Bring to next lesson. (If they are unable to
collect the label they should record information in their books and bring a picture of
the food).
Notes
‘Food and Digestion’ [LESSON 5]
Big Question: Why do we need to eat?
Science content
Explain what the main
components of a balanced
diet are used for.
Lesson Objectives
Science skills
Transferable skills
Plan and carry out research
(PLTS).
Provide constructive
support and feedback to
others (PLTS).
Communicate with others
(SEAL).
Key Words
Balanced Diet; Carbohydrate; Diet; Fat; Fibre; Mineral; Protein; Starch; Sugar;
Vitamin; Water
Resources:
Large sheets of paper.
Glue.
Pictures of different foods.
Access to computers with Internet.
Lesson Plan
STARTER
Prepare a classroom display as a collage to show examples of foods which are good
sources of each of the seven nutrients. Use the labels collected by the class for
their last homework, as well as the pictures to give extra support. Students could be
given the opportunity to explain their homework labels and where they fit in. [10
mins]
MAIN
1. Split students into 7 groups and tell them to carry out research into a particular
food group - give each group a different group to research. They should find out
what it’s needed for, how much is needed, where it can be found, etc. Say that they
can use diagrams to help explain their ideas. Explain that, at the end of the lesson,
each group will be asked to present their findings to the rest of the class and that
every student must play some part in the presentation. [20 mins]
2. Ask each group to present their findings. Other pupils should peer assess each one
and pick out three strengths and one feature which could have been improved. (Be
careful to ensure that the criticism isn’t about the students themselves, but about
the content of their presentations.) [20 mins]
PLENARY
1. Ask students to help complete a summary on the board – table with columns for
food group, how much is needed, what it is needed for. (This could be done after each
group’s presentation).
2. Students record summary. [10 mins]
Assessment Opportunities
Peer assessment – students comment on each group’s presentation.
Homework
Design a menu to show the food which a specified person should eat in a single day to
stay healthy. Give different students different types of people (e.g. an elderly man, a
pregnant woman, a runner, a toddler, a builder, a vegetarian, a Hindu). Tell pupils to
think about what that particular person needs which makes them different, and then
what foods would be appropriate to provide for those needs. Students should record
everything that the person would eat and drink during a single day.
Notes
‘Food and Digestion’ [LESSON 6]
Big Question: Why does bread taste different after chewing?
Science content
Explain where each food
group is digested, with
reference to action of
enzymes.
Lesson Objectives
Science skills
Use an existing model to
explain a phenomenon.
Transferable skills
Support conclusions,using
reasoned arguments and
evidence (PLTS).
Key Words
Absorbed; Amylase; Blood; Carbohydrase; Enzyme; Lipase; Protease; Salivary Gland;
Small Intestine; Stomach
Resources:
Laptop connected to Internet and interactive whiteboard.
Model small intestine – Visking tubing, starch solution, amylase, water bath,
equipment for starch and sugar tests.
Worksheet – Digestion a recap
Lesson Plan
STARTER
1. Invite volunteers to play ‘Digest Quest’ game (located on websitehttp://www.teachnutrition.org/default.aspx?SectionId=176) on interactive
whiteboard to review path through digestive system.
2. Review components of balanced diet with questioning. [15 mins]
MAIN
1. Show models/pictures of starch, sugar, protein, fat, vitamins, and minerals. Discuss
the differences between them, e.g. sugar, vitamins, and minerals consist of small
individual molecules, whereas starch, protein, and fat all consist of long complicated
molecules. Ask students where in the digestive system food is absorbed. Discuss
structure of small intestine including presence of villi. Ask students to predict and
explain which molecules would be easily absorbed. Discuss the role of fibre in the
diet and explain that our bodies are unable to break this down, so it is passed out of
the body as faeces. [10 mins]
2. Explain the model small intestine and set up as a demonstration. Leave apparatus
for 20 mins. [5 mins]
3. Meanwhile, explain the role of an enzyme – acting like a pair of scissors to cut up
large chain molecules into smaller soluble ones. Show the model/pictures of starch,
protein and fat molecules again and say the scissors (amylase/protease/lipase) break
them down into glucose, amino acids and fatty acids. All of these small molecules are
soluble and can be absorbed into the bloodstream. Draw diagrams to illustrate.
Discuss whereabouts in the digestive system each nutrient is broken down. [10 mins]
4. Students complete worksheet, recapping the organs of the digestive system and
their functions. [10 mins]
PLENARY
1. Collect results from experiment and explain what it shows. [10 mins]
Assessment Opportunities
Listening to and responding to ideas during discussions.
Homework
1. Tell pupils to chew a piece of bread for 5 – 10 minutes. They should then write
down what happens and try to explain why. (Bread should taste sweeter as starch is
broken down).
2. Write up model intestine experiment.
Notes
‘Food and Digestion’ [LESSON 7]
Big Question: What happens to a cheese sandwich when it is eaten?
Science content
Explain the journey of a
cheese sandwich through
the digestive system.
Lesson Objectives
Science skills
Use key scientific
vocabulary in written
work.
Transferable skills
Key Words
Absorption; Anus; Carbohydrate; Digestion; Dissolve; Enzyme; Fat; Gullet;
Hydrochloric Acid; Large Intestine; Liver; Mouth; Protein; Rectum; Small Intestine;
Stomach; Teeth
Resources:
The Journey of a Cheese Sandwich assessed task
Secondary resources – textbooks, library books.
Lesson Plan
STARTER
Introduce the task and discuss ideas for how it could be completed. Discuss food
groups contained within a cheese sandwich. [5 mins]
MAIN
Allow pupils to complete the task individually, with access to secondary resources
(class notes, text books, library books). [50 mins]
PLENARY
Discuss progress so far. [5 mins]
Assessment Opportunities
Completed tasks should be collected in to be marked according to criteria.
Alternatively, students could self-assess or peer-assess according to criteria.
Homework
Students may need extra time to complete the task at home.
Notes
This lesson could be completed as an extended homework task.