The shape of the lesson
By the end of the lesson, learners can
- What makes a diet balanced: Fill the plate in the sim with a day's food.
- Seven nutrients, their sources and jobs: For each nutrient learn one or two good sources and why the body needs it.
- Scurvy and rickets: Deficiency diseases are caused by a lack of a particular nutrient in the diet.
- Balanced diet: all the nutrients in the correct proportions and amounts.
- Energy: carbohydrates and fats; growth and repair: proteins.
- Scurvy = lack of vitamin C; rickets = lack of vitamin D or calcium.
- Fibre is not digested: it adds bulk for peristalsis and prevents constipation.
One picture every idea returns to
A balanced diet contains all the nutrients (carbohydrates, fats and oils, proteins, vitamins, mineral ions, fibre and water) in the correct proportions and amounts to stay healthy, and supplies enough energy for the person's needs. Scurvy is caused by a lack of vitamin C; rickets is caused by a lack of vitamin D or calcium.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, The right food, in the right amounts.. Every cell in your body is built from and powered by what you eat. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 13 min | Teach and check: What makes a diet balanced | Fill the plate in the sim with a day's food. Project tab 1 of the lab (Build a balanced diet on a plate) and let a student drive it while the class predicts. | Whole class, then pairs |
| 13 to 21 min | Teach and check: Seven nutrients, their sources and jobs | For each nutrient learn one or two good sources and why the body needs it. | Pairs |
| 21 to 30 min | Teach and check: Scurvy and rickets | Deficiency diseases are caused by a lack of a particular nutrient in the diet. | Corners |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 19 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Scurvy and rickets, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Corners
Put one answer or viewpoint in each corner of the room. Students move to the corner they agree with, justify the choice to a partner there, then hear one voice from each corner before the reveal.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| A balanced diet is not just "eating healthy food" or "eating a bit of everything". | You must say it contains all the nutrients in the correct proportions (amounts). |
| Rickets can be caused by a lack of vitamin D even when there is enough calcium in the diet, because vitamin D is needed to absorb the calcium. | Name both possible causes. |
Diet: worksheet
6 questions, 19 marks. Written in the style of the papers; no past paper question is reproduced.
Describe what is meant by a balanced diet.
For each of the following, name one good dietary source and state why the body needs it: (a) protein, (b) iron, (c) calcium, (d) carbohydrate.
A teenager needs about 1000 mg of calcium a day. A glass of milk contains 300 mg and a portion of cheese contains 240 mg. (a) Calculate the percentage of the daily need supplied by one glass of milk and two portions of cheese. (b) State how much more calcium is needed to reach 100%.
Explain why a person whose diet lacks vitamin D may develop rickets even though they drink plenty of milk.
Fibre is not digested by humans. Explain why it is still an important part of the diet.
The table shows the nutrients in 100 g of three foods.
| Food | Protein / g | Fat / g | Vitamin C / mg | Fibre / g |
|---|---|---|---|---|
| A | 25 | 12 | 0 | 0 |
| B | 3 | 0.3 | 80 | 3 |
| C | 8 | 0.5 | 0 | 7 |
(a) Suggest which food is oily fish, which is broccoli and which is beans. (b) Which food would best help to prevent scurvy? Give a reason. (c) A diet made only of food A would not be balanced. Give two reasons.
Answer key and marking notes
- A diet containing all the nutrients: carbohydrates, fats and oils, proteins, vitamins, mineral ions, fibre and water.
- In the correct proportions and amounts to meet the body's needs (including enough, but not too much, energy).
- (a) Protein: meat, fish, eggs or beans; for growth and repair of cells (making enzymes and antibodies).
- (b) Iron: red meat, liver or beans; to make haemoglobin in red blood cells.
- (c) Calcium: milk or cheese; for strong bones and teeth (and blood clotting).
- (d) Carbohydrate: rice, bread or potatoes; as the main source of energy for respiration.
- (a) Total = 300 + (2 × 240) = 780 mg.
- Percentage = 780 ÷ 1000 × 100 = 78%.
- (b) 1000 − 780 = 220 mg more is needed.
- Milk provides calcium, which is needed for strong bones.
- Vitamin D is needed for the body to absorb calcium from the food.
- Without vitamin D little calcium is absorbed, so the bones are soft and weak and bend: rickets.
- Fibre adds bulk to the food in the intestines.
- The muscles of the gut wall can push bulky food along more easily (peristalsis).
- This prevents constipation (food and faeces move through at a steady rate).
- (a) A = oily fish (high protein and fat), B = broccoli (high vitamin C), C = beans (protein and high fibre).
- (b) B, because it contains the most vitamin C, and a lack of vitamin C causes scurvy.
- (c) It contains no vitamin C, so scurvy could develop.
- It contains no fibre (and little carbohydrate), so constipation is likely and too much energy would come from fat.
8 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Which nutrient is needed mainly for the growth and repair of body cells?
- AProtein
- BCarbohydrate
- CFibre
- DVitamin C
Which food is the best source of iron?
- ARed meat
- BMilk
- COranges
- DButter
What causes scurvy?
- AA lack of vitamin C in the diet
- BA lack of vitamin D in the diet
- CA lack of iron in the diet
- DEating too much fat over a long time
Why does a person who eats very little fibre often suffer from constipation?
- AThere is too little bulk for the gut muscles to push along
- BFibre is digested to glucose, which softens the faeces
- CWithout fibre, no water can be absorbed in the colon
- DFibre contains enzymes that break down the faeces
The bar chart shows the percentage of the daily need met by one teenager's diet. Which deficiency disease is this teenager most at risk of?
- AScurvy
- BRickets
- CAnaemia
- DObesity
Using the bar chart, a teenager needs 25 g of fibre a day. How much more fibre, in grams, would bring the diet up to 100% of the daily need?
- A16.25 g
- B8.75 g
- C65 g
- D35 g
A child with dark skin living in a cloudy northern city drinks plenty of milk but develops bowed legs. Which explanation is most likely?
- AToo little vitamin D, so calcium from the milk is not absorbed well
- BToo little calcium, because milk contains no calcium at all
- CToo little vitamin C, so the bones bleed and soften
- DToo little iron, so the bones cannot carry enough oxygen
Which change in diet would be most suitable for a person who is very active, such as a long-distance runner in training?
- AMore carbohydrate, to provide extra energy for respiration
- BLess water, to reduce the mass carried while running
- CMore vitamin C, to provide extra energy for the muscles
- DLess protein, because muscles do not need repairing
Quiz key
Proteins are digested to amino acids, which cells use to build new proteins for growth and repair, including enzymes and antibodies. Carbohydrate is mainly a source of energy for respiration. Fibre is not digested; it adds bulk to help food move through the gut. Vitamin C keeps skin, gums and blood vessels healthy but is not the building material for new cells.
Red meat (and liver, beans and dark green vegetables) is a good source of iron, needed to make haemoglobin. Milk is a good source of calcium but contains very little iron. Oranges are a rich source of vitamin C. Butter is mainly fat and provides energy, with almost no iron.
Scurvy is a deficiency disease caused by a lack of vitamin C, found in citrus fruit and fresh vegetables. A lack of vitamin D (or calcium) causes rickets, not scurvy. A lack of iron leads to anaemia. Too much fat leads to obesity, which is not a deficiency disease.
Fibre adds bulk to the contents of the intestines, so the muscles of the gut wall can push food along by peristalsis; with too little bulk, food and faeces move slowly and constipation results. Humans cannot digest fibre, so it is not turned into glucose. Water is still absorbed in the colon without fibre; in fact too much is absorbed when food moves slowly. Fibre contains no digestive enzymes.
Vitamin C reaches only 12% of the daily need, by far the lowest, and a lack of vitamin C causes scurvy. Rickets is caused by a lack of vitamin D or calcium, but these reach 90% and 95%. Anaemia is caused by a lack of iron, which reaches 80%. Obesity comes from too much energy in the diet, not from a deficiency shown on this chart.
The diet provides 35% of 25 g = 0.35 × 25 = 8.75 g, so 25 − 8.75 = 16.25 g more is needed. 8.75 g is the amount already eaten, not the shortfall. 65 g treats the missing 65% as grams. 35 g simply reads the bar height as a mass.
Vitamin D is made in the skin in sunlight and is needed to absorb calcium. With little sunlight (and dark skin making less vitamin D), calcium is poorly absorbed even though milk supplies plenty, so the bones are soft and bend: rickets. Milk is a rich source of calcium, so calcium intake is not the problem. A lack of vitamin C causes scurvy, not bowed legs. Iron is needed for haemoglobin, not bone strength.
An active person respires more, so needs more energy, mainly from carbohydrate. They lose more water in sweat, so need more water, not less. Vitamins do not provide energy. Training damages and builds muscle, so protein is needed for growth and repair, not less of it.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.