KS3 scheme of work for Biology

Sprowston High School

2002/3.

Unit 8A Food and digestion
About the unit
In this unit pupils learn:
o about different foods and how they can be combined to produce a balanced diet
o how food is broken down by digestion so it can be used by the body, for energy, growth and repair
In scientific enquiry pupils:
o consider the extent to which evidence about diet can lead to firm conclusions
o use a model to explore digestion
o use chemical tests to identify food types
o present and interpret data from secondary sources
o draw conclusions from observations and explain these using scientific knowledge
o investigate a question about nutrition using secondary sources of information
This unit is expected to take approximately 8 hours.
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Where the unit fits in
This unit draws on ideas about food and nutrition developed in the key stage 2 programme of study. It builds on unit 5A 'Keeping healthy' in the key stage 2 scheme of work and on unit 7A 'Cells'.
The particle model of matter is introduced in unit 7G 'Particle model of solids, liquids and gases' and is revisited in this unit in the context of digestion.
The unit relates to other units that focus on life processes in humans: unit 8B 'Respiration' and unit 9B 'Fit and healthy', which revisits the concept of a healthy diet.
The energy transfer ideas of unit 7I 'Energy resources' are used in the context of digestion. Energy should be distinguished from 'stuff' (food as the energy resource or fuel).
This unit relates to unit 8A(i) 'Exploring materials (food)' and unit 9A(i) 'Selecting materials (food)' in the design and technology scheme of work.
Expectations
At the end of this unit
in terms of scientific enquiry
most pupils will: use secondary sources of information to generate graphs or displays relevant to questions asked; recognise that interpretation of evidence about questions of health and diet may be difficult; identify and control relevant variables when investigating the action of an enzyme
some pupils will not have made so much progress and will: find information from selected secondary sources about food and diet; generate graphs or displays relevant to questions asked; with help, control relevant variables when investigating the action of an enzyme
some pupils will have progressed further and will: choose secondary sources to provide the information needed about food and diet; explain why interpretation of evidence about questions of health and diet may be difficult
in terms of life processes and living things
most pupils will: name nutrients, fibre and water as part of a balanced diet, identifying examples of foods in which they are found, and describe the role of the main nutrients in the body; use a model to describe how large molecules are broken down during digestion and describe the role of blood in transporting products of digestion around the body
some pupils will not have made so much progress and will: name some groups of nutrients and identify some examples of foods in which they are found; describe a balanced diet; recognise that blood transports products of digestion around the body
some pupils will have progressed further and will: explain why some nutrients have to be broken down before they can be used by the body and why some foods cannot be digested by humans
Prior learning
It is helpful if pupils:
o know that food is needed for activity and growth, and that an adequate and varied diet is needed to maintain health
o know that matter, including food, consists of particles, eg molecules, which can differ in size
o recognise that food provides energy for the body
Health and safety
Risk assessments are required for any hazardous activity. In this unit pupils:
o carry out chemical tests on a range of foods
o investigate the effect of saliva on starch
o plan and carry out their own investigation into enzyme activity
Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher's guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.
Through the activities in this unit pupils will be able to understand, use and spell correctly:
o scientific words relating to the structure of organisms, eg intestine, villus
o more specialised words relating to nutrition, eg carbohydrate, protein, enzyme
o words and phrases with similar but distinct meanings, eg take in and absorb, feeding and digestion
o words that extend their vocabulary, eg absorption
Language for learning
Through the activities pupils could:
o show relationships between ideas by using links which show purpose, eg in order to, so that, and reservations, eg although, unless, if
o select relevant information and link to other information, from a range of sources
o distinguish facts from hypotheses/theories/opinions and consider how far information is complete and helpful
Resources
Resources include:
o secondary sources to explore the constituents of food, eg diet software, CD-ROMs, dietary information leaflets, video clips of TV advertisements, other literature, which may include articles from magazines
o a range of foodstuffs for testing, sufficient to provide several samples rich in each of the major chemical groups in food, including foods that are found in the diet of other countries
o illustrative material relating to advertising claims for foods, eg from magazines
o database and spreadsheet software
o simulation software illustrating digestion and transport of substances in the blood
o a collection of food packaging, including cereal packets showing nutritional contents
o media reports, magazine, newspaper and television advertisements relating to food and diet
Out of school learning
Pupils could:
o o visit a supermarket to find out more about foods
o look at menus and labels in fast-food outlets
o read articles in magazines and newspapers about issues relating to food and diet, eg for athletes, pregnant women, very young children
o find out about conflicts in dietary advice, and world food shortages
o extend their ideas about diet during holidays and visits to other families
o use the internet to find information and advice on food and diet,
eg www.nutrition.org.uk
Overview: what food contains diets digestive system enzymes products of digestion

Lesson 8/A/1 Food and digestion

National Curriculum Statements: 2a. about the need for a balanced diet containing carbohydrates, proteins, fats, minerals, vitamins, fibre and water, and about foods that are sources of these

Learning objectives

o that foods are a source of raw materials for the body
o that foods are the energy resource to maintain the body's activities (growth, repair and movement) Learning outcomes
o identify some reasons why food is important, eg as raw material, for growth, for energy

Key Words
carbohydrates, fats, vitamins, minerals, fibre, water, digestion, growth, repair, movement

Possible teaching activities

Concept mapping in small groups. Pupils draw diagram of body on A3 paper using what they already know. They label it, stating where they think various processes go on. Use prompts: location of digestive organs, the processes that go on, where does the food go, what happens to it…
o Ask pupils to use the nutritional information panel from cereal packets to identify the main nutrients contained in food, and establish that carbohydrates, proteins, fats, fibre and water form the bulk of food.
Use this information to improve the concept map.
Go through each concept map with the whole group.

Extension/homework.

Find out and write down the foods that are good sources of protein, carbohydrates, fat.
pupils could be asked to find out about how mammals in desert conditions obtain sufficient water in their diet.
Opportunity for silent reading
Differentiation
Lower ability read and answer Q's from CORE SCIENCE 1, p22-23; CORE SCIENCE 2, p30-33. Higher ability read and answer Q's World of Science 2, p43.
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Equipment needed
Differentiation
Lower ability: CORE SCIENCE 1, CORE SCIENCE 2. Higher ability: World of Science 2.
A3 paper, big felt pens.
Food packets

Do not forget to book computer room for 8/A/3
Overview: what food contains diets digestive system enzymes products of digestion

Lesson 8/A/2 Chemicals that food contain

National Curriculum Statements: 2a. about the need for a balanced diet containing carbohydrates, proteins, fats, minerals, vitamins, fibre and water, and about foods that are sources of these

Learning objectives

o to use chemical tests to identify proteins, carbohydrates and fats
o to work safely with chemicals
o that foods contain a mix of proteins, carbohydrates, fats, vitamins, minerals, fibre and water
Learning outcomes
· identify foods which are rich in particular nutrients
o use chemical tests to identify proteins, carbohydrates and fats
o work safely with chemicals
o use chemical tests to identify proteins, carbohydrates and fats
o work safely with chemicals

Key words
nutrients, proteins, carbohydrates, fats, mineral, vitamin

Possible teaching activities

o Demonstrate food tests (ref. P183-188, Teachers Guide 2) to identify protein, starch, sugar ensuring that pupils are aware of the health and safety requirements for these tests.
o Provide a range of foods and ask pupils working in groups to use the food tests to identify the presence of nutrients in the foods using World of Science 2, p44-5. Each group could look at one food test.

Differentiation
Lower ability use helpsheets 13H1 and 13H2

o Discuss with pupils the importance of water in the diet, what the sources of water are and whether it should or should not be counted as a nutrient.
o identify foods which are rich in particular nutrients

Extension/homework.

List the foods eaten in a day; organise into breakfast, lunch, dinner, snacks and include drinks. This will be used next lesson.

Differentiation
Lower ability: worksheet 13.2F. Higher ability: worksheet 13.2H
Pupils could be asked to find out about how mammals in desert conditions obtain sufficient water in their diet.
Information to learn:
test Positive result
Starch Add iodine Iodine turns black
Glucose Heat with benedicts solution Turns green, orange, brick red
Protein Add sodium hydroxide, then a drop of copper sulphate Turns mauve/violet
Fat Add alcohol Solution goes opaque
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Safety
- appropriate risk assessments should be made in relation to the proteins, carbohydrates and fats used and the reagents used to test for them
- very dilute sodium hydroxide
(0.2 mol dm-3) should be used in the Biuret test for protein
- Benedict's (not Fehling's) solution should be used in the tests for sugars
- if ethanol (highly flammable) is used to test for fats, ensure no naked flames are used and remind pupils how to heat a test tube of liquid safely
- pupils should not eat the food tested because of possible contamination
- beware of foods containing nuts.
If pupils with known allergies are present, follow appropriate procedures after risk assessment
Equipment needed
World of Science 2.
Differentiation
Lower ability: worksheet 13.2F.
Helpsheet 13H1, 13H2 Higher ability: worksheet 13.2H
Overview: what food contains diets digestive system enzymes products of digestion

Lesson 8/A/3 Looking at my diet

National Curriculum Statements: 2a. about the need for a balanced diet containing carbohydrates, proteins, fats, minerals, vitamins, fibre and water, and about foods that are sources of these

Learning objectives

o that vitamins and minerals are present in smaller amounts than the other constituents of food
o how to search for information in databases or spreadsheets
o to use and interpret
ICT-generated graphs

Learning outcomes
o use ICT to produce graphs or displays relevant to the question asked
o use data to show that vitamins and minerals are present in foods in smaller amounts than the other nutrients
o describe, eg in an information leaflet, good sources of one nutrient and the importance of that nutrient in the diet

· construct a Venn diagram showing the combinations of nutrients in each food sample tested

Key words
Proteins, carbohydrates, fats, vitamins, minerals, balanced diet, energy

Possible teaching activities

o Develop pupils' understanding of a balanced diet by using software on diet containing information about the nutritional content of a range of foods. Use the computer room.
· Analyse food eaten in a 24 hour period using worksheet. Make comparisons with RDA.
Differentiation
· Lower ability groups use worksheet. o Higher ability
Help pupils to frame appropriate questions to investigate, eg Which foods contain starch and fat?, and to use the spreadsheet to produce and interpret graphs. Ask them to compare the results obtained with the Venn diagram from the previous activity and to suggest reasons for differences.

Extension/homework.
o Help groups of pupils to use the results of their investigations to produce a summary leaflet about one type of food constituent, including information about foods that are a good source of it and the role of this food constituent in the diet.
o Bring together all the leaflets as a class booklet and establish the main role of each type of food in the diet.
o Pupils could use information in a database or spreadsheet to answer questions, eg
- Are foods containing protein more expensive than other foods?
- What are the sources of protein for a vegetarian?
- How does the nutritional content of a prepared microwave meal compare with that of a similar freshly prepared cooked meal?
Pupils could find out why we need vitamins.
Information to learn.
Mineral Found in Needed for
Iron meat Blood
Calcium milk Teeth/bones
Sodium salt Nerves
Iodine Sea food Thyroid gland

____________________________________________________________________________________Points to note
o Pupils should be reminded that information is normally given in terms of 100g of food and that this may not be a standard portion. They could scale the values up or down according to the standard portions and assess the nutritional value of a typical meal. This provides an opportunity to reinforce ideas about making fair comparisons.
Internet
http://dawp.anet.com/on diet

Equipment needed
Worksheet on food analysis.
Overview: what food contains diets digestive system enzymes products of digestion

Lesson 8/A/4 Looking at other diets

National Curriculum Statements: 2a. about the need for a balanced diet containing carbohydrates, proteins, fats, minerals, vitamins, fibre and water, and about foods that are sources of these

Learning objectives
o that a healthy diet contains a balance of foodstuffs
o different individuals need different diets
o that protein is important for growth and repair and that carbohydrates and fats more commonly provide energy Learning outcomes

o identify that different individuals need different diets
o identify the main role of proteins, carbohydrates and fats in
the diet

Key words
diet, balanced diet, energy, protein, carbohydrate, fat, vitamin, minerals

Possible teaching activities
o Introduce the idea that there are many different healthy and balanced diets by inviting pupils from a variety of backgrounds to describe some of the main features of their own or their family's diet. Suggest that pupils ask senior members of their family to describe the type of diet they had when they were children.
· Use worksheets to look at following
- Can too much salt be harmful?
- What is a healthy diet?
- Should children and adults have the same diet?
- Are low-calorie alternatives always preferable?
- How do diets of different cultures differ?
- What foods should you eat to reduce the chance of heart disease?
- What do athletes eat at different stages of training?
- What does a pregnant woman need in her diet?
- What are 'organic' foods and how are they different from other foods?
- Are breakfast cereals really good for you?
-
o Raise the issue of what exactly is meant by a 'healthy' balanced diet.
o explain that a healthy diet contains a balance of six groups of chemicals (proteins, carbohydrates, fats, vitamins, minerals, fibre) and water
o Discuss with pupils what they have found out and the extent to which they have confidence in the information they used.
o Ask pupils to produce a report of their findings and conclusions in an interesting and appropriate format, eg display work, an advisory leaflet for a particular target group, a class debate, a radio interview script.
o Remind pupils about earlier work on food chains and contrast the diet of animals with the range of the human diet.
Opportunity for silent reading
Differentiation
Low ability: CORE SCIENCE 1 p22-23, p46-7, p48-9. High ability: WORLD OF SCIENCE 2 p47, Q1-6, p48 Q1-4.

Extension/home work
: pupils could be asked to find out about the diet of another mammal and to compare the range of nutrients it provides with those in the human diet.
Differentiation
Worksheet 13.1F Food
Worksheet 13.2F Vitamins Worksheet 13.1H Food
Worksheet 13.2H Vitamins

Worksheet 8/A/4 A, B, C, D balanced diet.

pupils could find out about the special diets of other pupils and consider the reasons why the balance of constituents within these diets is different and important.
Found Used for
Carbohydrates Bread/potatoes/cereals Energy
protein Meat/eggs/fish Building cells
Fats Butter/oil/cream Energy
Vitamins Veg/fruit/cereal Vital processes
Roughage Veg/cereals/fruit Digestion
Water All cells need this Chemical reactions occur in it

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Points to note
o Teachers will be aware of the need to ensure that pupils are sensitive to differences between each other's individual diets as well as the diet of their families and friends.
o Whilst the concept of a balanced diet is easy for pupils to understand, the media present much conflicting dietary advice, which may be biased according to its source.
o This provides an opportunity for considering an area of science in which our knowledge is incomplete and interpretation of the available evidence is difficult.
o Leaflets and posters providing information on diet are available from many sources, including health promotion units and health organisations, eg the British Heart Foundation, British Nutrition Foundation, food manufacturers, food marketing organisations, eg The National Dairy Council, food retailers and the media.
o Many of these organisations also provide internet sites presenting dietary information. Pupils could be encouraged to explore these.

Internet site
www.healthworld.com/clinic/therapy/nutrit/role.htm
Equipment needed
Class and homework sheets on balanced diet.
Worksheet 8/A/4 A, B, C, D balanced diet.
Differentiation
Lower ability: CORE SCIENCE 1, Worksheet 13.1F, 13.2F Higher ability: WORLD OF SCIENCE 2, worksheet 13.1H, 13.2H

Overview: what food contains diets digestive system enzymes products of digestion

Lesson 8/A/5 The digestive system.

National Curriculum Statements: 2b. the principles of digestion, including the role of enzymes in breaking down large molecules into smaller ones

Learning objectives
o that the digestive system consists of a tube through which food passes
o to interpret the relationship between a model gut and the digestive system
o to suggest explanations for observations
o that foods contain starch, protein and fat, which have molecules that are too large to be absorbed by the body
o that sugars, vitamins and minerals are generally smaller and can be absorbed by the body
o that large molecules are broken down by enzymes in the gut to form smaller molecules, which pass through the wall of the small intestine
o to represent a complex process using diagrams and text
o how models can be used to represent and explain complex
processes Learning outcomes
o describe how food passes along a digestive tube which runs through the body
o offer suggestions about what happens to food as it passes through this tube

o state that small molecules can pass through the wall of the small intestine
o explain that starch, protein and fat molecules are too large to be absorbed
o explain that specific vitamins and minerals are generally smaller and can be absorbed by the body
o produce a sequence of diagrams to illustrate that larger molecules are broken down to form smaller molecules in the gut
o describe the processes involved, eg by drawing diagrams,
by using models, in writing
o make links between the model gut and the digestive
system
Key words
digestion, absorption, excretion, egestion, ingestion, faeces, oesophagus, stomach, intestine, anus

Possible teaching activities
o Ask pupils for their ideas about what happens to food once it has been eaten. Develop the idea that food enters a tube running through the body, and that this, and associated organs, make up the digestive system. Build up their suggestions into a sequence of events commencing with feeding, followed by absorption and ending with elimination of faeces.
produce a sequence of diagrams to illustrate that larger molecules are broken down to form smaller molecules in the gut

o Explain that what happens to food inside this tube can be explored using a model,
differentiation
Lower ability
Use sand and chick pea in sieve model. WORLD OF SCIENCE 2 teachers guide p197. Higher ability
eg a model gut made from visking tubing filled with a 'starch meal'; a software simulation. Ask pupils about how they tested for starch earlier and help them to test the contents of the 'gut' and the surrounding water for starch. Ask pupils to explain their observations and to consider the implications of nutrients from food entering the body.

o Ask pupils to interpret their findings in the light of their previous assumptions.
.

Draw digestion diagram from p49 WORLD OF SCIENCE 2. Do Q1-4.

Opportunity for silent reading
Differentiation
Lower ability
CORE SCIENCE 1 p50-1, 52-3, p54-5.

Extension/home work.
Differentiation
Worksheet 13.4F Worksheet 13.4H
pupils could produce a 'flicker-book' animation to represent the process.

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Equipment needed
differentiation
Lower ability: sand and chick pea in sieve model, CORE SCIENCE 1 Higher ability: starch, visking tubing, iodine, benedicts, pipettes, WORLD OF SCIENCE

CORE SCIENCE 2 WORLD OF SCIENCE 2

Overview: what food contains diets digestive system enzymes products of digestion
Lesson 8/A/6 Digesting food.
National Curriculum Statements: 2b. the principles of digestion, including the role of enzymes in breaking down large molecules into smaller ones
Learning objectives
o that food is digested by enzymes in the gut to form smaller molecules
· to identify factors relevant to a particular context
o to plan how to control variables
o to explain their results using knowledge of the human digestive system
o to show relationships between ideas by using links that show purpose and reservation
o to frame a question that can be investigated Learning outcomes
o state that food is digested by enzymes in the gut to form smaller molecules and that these pass into the blood

o use scientific knowledge to explain observations
suggest relevant variables, eg pH, temperature
o identify a way to keep variables, eg temperature, constant
o identify the conditions under which digestion occurs, eg at a temperature of 37ºC, and relate these to their results
Key words
enzymes, digestion, absorption
Possible teaching activities
o Through questioning, elicit pupils' ideas about digestive enzymes as a means of breaking down larger molecules. Establish that the water outside the tubing in the model represents the blood system. Ask them to explain the process, eg using animations from CD-ROMs or video, or interlocking bead models of large molecules. Ask pupils to draw a sequence of diagrams and then write an explanation in their own words
Pupils could do a play or radio script or video that could be viewed by rest of class.
Opportunity for silent reading
Differentiation
CORE SCIENCE 2 p32-3, p45. WORLD OF SCIENCE 2 p52 Q1-4.
o Remind pupils of the range of food types with large molecules and explain that in addition to enzymes the conditions inside the gut assist the breakdown of large molecules, eg body temperature. Ask the pupils to discuss what other substances are found in the stomach. After the discussion inform the pupils that hydrochloric acid is produced by the lining of the stomach.
o Provide them with an opportunity to investigate the action of a particular enzyme, eg saliva on starch (WORLD OF SCIENCE 2 p53)
o Ask pupils to suggest what might affect how well the enzyme digests the food, eg pH, temperature, and help them to plan an investigation, identifying what they are going to measure and which variables they will need to control. Ask pupils to produce an account of their investigation, relating what they found out to the conditions in the gut.
Extension/homework
pupils could find out which is the best washing powder for an egg yolk stain, eg biological or non-biological. Be aware that some pupils may be allergic to biological washing powders.
Write up practical.
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Points to note
o At this stage, pupils do not need to know the names of specific digestive enzymes, although some pupils might find these out for themselves.
o In unit 7E 'Acids and alkalis' pupils may have found out about the use of acid in the human digestive system.
o The effect of pH changes on enzyme activity could be monitored using ICT.
Safety
- ensure pupils use their own saliva and that used test tubes are placed in disinfectant. Staff who clean apparatus should use gloves
- pupils' plans must be checked for health and safety before practical work begins. Remind pupils how to safely heat test tubes of acid and other substances
Equipment needed
Body model and digestive system sheet.
Starch, iodine, spotting tiles, HCl, kettle, WORLD OF SCIENCE 2
Internet www.woodrow.org/teachers/ci/1988/starch.htmt

Overview: what food contains diets digestive system enzymes products of digestion

Lesson 8/A/7 Where are the products of digestion used?

National Curriculum Statements: 2c. that the products of digestion are absorbed into the bloodstream and transported throughout the body, and then waste material is egested

Learning objectives
o that the products of digestion are transported in the blood to other parts of the body
o that some food material cannot be digested and is egested
that foods are the energy resource to maintain the body's activities (growth, repair and movement) Learning outcomes
o state that the blood transports products of digestion to every cell in the body
o use models to describe how smaller molecules are transported in the blood
o state that some food material cannot be digested and is passed out of the body as faeces

Key words
blood, faeces, digestion
Possible teaching activities
o Remind pupils about the way in which the body uses food, eg for energy, for growth. Ask them how the products of digestion reach other parts of the body.
o Ask pupils which of the food types they hadn't considered during the work on the products of digestion. Establish that fibre and undigested food is passed through the gut and egested in faeces.
Opportunity for silent reading
Differentiation
Lower ability: CORE SCIENCE 2 p34-5. Higher ability: WORLD OF SCIENCE 2 p54 Q1-4.
Reviewing work
o to relate knowledge and understanding of food types to the processes of digestion
o Provide pupils with an appropriate selection of terms related to food and digestion and ask them to use these to make a new concept map, given that they have finished the course. Discuss pupils' maps with them, asking them to identify areas of difficulty and challenging them to make and explain new connections.
o identify appropriate connections between ideas in this unit and explain their reasoning
o A concept map can show connections between different ideas in a particular topic. Pupils may have made concept maps in key stage 2.
Revise for test next lesson and then do 2 CASE lessons
Extension/homework Pupils could be asked to find out why grass is not a source of food for humans. Revise for test.
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Points to note
o At key stage 2 pupils are likely to have learnt about blood being pumped around the body by the heart, but not about the role of the blood in transporting the products of digestion to other parts of the body. The body's use of glucose in respiration is covered in unit 8B 'Respiration'.
Equipment needed
Differentiation
Lower ability: CORE SCIENCE 2 Higher ability: WORLD OF SCIENCE 2

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