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Science lesson plan · 7th grade (Year 8 in England) · 30 minutes

Test foods for starch, sugar, protein and fat

Human body and health

CCSS NGSS.MS-LS1-7CCSS NGSS.SEP 3England: KS3 Biology: Nutrition and digestionEngland: GCSE Combined Science: Organisation (required practical: food tests)

Objective and success criteria

Students will: Test foods for starch, sugar, protein and fat.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Food groups, nutrients and what each one does

Leads to: the next skill in this area.

Materials: Stopwatches, Body diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 4 min

  • Quick retrieval from earlier learning (Food groups, nutrients and what each one does). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which nutrient group matches this: keeps food moving through the intestines? (proteins / vitamins and minerals / fibre (fiber) / lipids (fats and oils)) → fibre (fiber)Prompt: Energy, growth, stored energy, small amounts for health, or keeping the gut moving?
  2. A sandwich contains 25 g of carbohydrate, 3 g of protein and 9 g of fat. Carbohydrate and protein each release 17 kJ per gram; fat releases 37 kJ per gram. How much energy does it provide, in kJ? → 809 kJPrompt: Work out the energy from each nutrient separately.
  3. A sailor long ago ate no fresh fruit or vegetables for months and got bleeding gums (scurvy). What was missing? (fat / protein / vitamin C / fibre (fiber)) → vitamin CPrompt: Citrus fruits such as oranges and lemons cured it.

Hook · 3 min

  • Ask everyone to find their pulse, then jump for 30 seconds and find it again.
  • Share the objective: Test foods for starch, sugar, protein and fat. Read the success criteria together.

I do: model it · 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: A food sample gives this result: iodine turns blue-black. Which nutrient is present?
  • Step 1: Iodine solution turns from orange-brown to blue-black with starch.
  • Step 2: So the answer is: starch
  • Answer: starch
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 6 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. A food sample gives this result: Benedict's solution turns brick-red when heated. Which nutrient is present? (starch / sugar (reducing sugar) / protein / fat (lipid)) → sugar (reducing sugar)Prompt: Each test is used for just one nutrient.
  2. A food was tested. Iodine: blue-black. Benedict's (heated): brick-red. Biuret: purple. Which nutrients does it contain? (protein / starch / starch and sugar / starch and sugar and protein) → starch and sugar and proteinPrompt: A colour change means the nutrient is present.

You do: independent practice · 7 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Why should you wear eye protection when doing the Benedict's test? (Benedict's solution is radioactive / Iodine glows in the dark / It involves heating in a hot water bath and the reagent is an irritant / The food might explode) → It involves heating in a hot water bath and the reagent is an irritantPrompt: What is different about this test?
  2. A food was tested. Iodine: blue-black. Benedict's (heated): brick-red. Biuret: purple. Which nutrients does it contain? (starch / starch and sugar / starch and protein / starch and sugar and protein) → starch and sugar and proteinPrompt: A colour change means the nutrient is present.

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Food groups, nutrients and what each one does.
  • Use concrete materials: stopwatches.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.

Free lesson plan from eurekami.com/lesson-plan-builder

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Test foods for starch, sugar, protein and fat

Name

Date

Score/ 6

  1. Question 1

    Why must food be ground up and mixed with water before testing?

    • A. to change its colour
    • B. to kill bacteria
    • C. to make it taste better
    • D. so the nutrients dissolve and can react with the reagents

  2. Question 2

    A food sample gives this result: ethanol then water gives a cloudy white layer. Which nutrient is present?

    • A. starch
    • B. sugar (reducing sugar)
    • C. protein
    • D. fat (lipid)

  3. Question 3

    A food was tested. Iodine: stays orange-brown. Benedict's (heated): stays blue. Biuret: purple. Which nutrients does it contain?

    • A. sugar and protein
    • B. starch and sugar
    • C. protein
    • D. starch and sugar and protein

  4. Question 4

    A student adds iodine to plain water as well as to the food samples. Why?

    • A. to test the water for protein
    • B. as a control to compare the colours against
    • C. to save iodine
    • D. to make the iodine stronger

  5. Question 5

    A food sample gives this result: Benedict's solution turns brick-red when heated. Which nutrient is present?

    • A. starch
    • B. sugar (reducing sugar)
    • C. protein
    • D. fat (lipid)

  6. Question 6

    A food was tested. Iodine: blue-black. Benedict's (heated): stays blue. Biuret: stays blue. Which nutrients does it contain?

    • A. sugar
    • B. starch
    • C. starch and sugar
    • D. starch and protein

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Answer key: Test foods for starch, sugar, protein and fat

  1. 1. D. so the nutrients dissolve and can react with the reagents

  2. 2. D. fat (lipid)

  3. 3. C. protein

  4. 4. B. as a control to compare the colours against

  5. 5. B. sugar (reducing sugar)

  6. 6. B. starch