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Science lesson plan · 7th grade (Year 8 in England) · 45 minutes

Digestive enzymes and the molecules they make

Human body and health

CCSS NGSS.MS-LS1-3CCSS NGSS.HS-LS1-6England: KS3 Biology: Nutrition and digestionEngland: GCSE Combined Science: Organisation

Objective and success criteria

Students will: Digestive enzymes and the molecules they make.

  • 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: Trace a meal through the digestive system; Food groups, nutrients and what each one does

Leads to: How enzymes work: active sites, temperature and pH

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

Warm-up · 5 min

  • Quick retrieval from earlier learning (Trace a meal through the digestive system; 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: store energy and keep the body warm? (carbohydrates / lipids (fats and oils) / vitamins and minerals / fibre (fiber)) → lipids (fats and oils)Prompt: Energy, growth, stored energy, small amounts for health, or keeping the gut moving?
  2. Where is most water absorbed back into the body? (liver / large intestine / stomach / mouth) → large intestinePrompt: It is the part just before the waste leaves.
  3. Which nutrient group matches this: found in rice, bread and pasta? (carbohydrates / lipids (fats and oils) / fibre (fiber) / vitamins and minerals) → carbohydratesPrompt: Energy, growth, stored energy, small amounts for health, or keeping the gut moving?

Hook · 5 min

  • Ask everyone to find their pulse, then jump for 30 seconds and find it again.
  • Share the objective: Digestive enzymes and the molecules they make. Read the success criteria together.

I do: model it · 10 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Which enzyme is described here: breaks fats down into fatty acids and glycerol?
  • Step 1: Lipase breaks lipids into fatty acids and glycerol.
  • Step 2: So the answer is: lipase
  • Answer: lipase
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 10 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. Which enzyme is described here: breaks starch down into sugars? (amylase (a carbohydrase) / protease / lipase) → amylase (a carbohydrase)Prompt: The enzyme's name often sounds like the food it breaks down.
  2. Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 6 min 30 °C: 3 min 40 °C: 7 min 50 °C: 9 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C? → 30 °CPrompt: Fastest means the shortest time.

You do: independent practice · 10 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 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Why must large food molecules such as starch be digested? (They are poisonous / They contain no energy / They are too big to pass through the gut wall into the blood / They taste bad) → They are too big to pass through the gut wall into the bloodPrompt: Think about size and absorption.
  2. Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 8 min 30 °C: 9 min 40 °C: 3 min 50 °C: 8 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C? → 40 °CPrompt: Fastest means the shortest time.

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: Trace a meal through the digestive system.
  • 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

  • Move on to: How enzymes work: active sites, temperature and pH.
  • 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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Digestive enzymes and the molecules they make

Name

Date

Score/ 8

  1. Question 1

    Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 7 min 30 °C: 4 min 40 °C: 8 min 50 °C: 8 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C?

    Answer°C

  2. Question 2

    A piece of bread tastes sweeter after you chew it for a long time. Why?

    • A. Chewing adds sugar
    • B. Amylase in saliva breaks starch into sugar
    • C. The bread gets warmer
    • D. Saliva contains lipase that makes sugar

  3. Question 3

    Which enzyme is described here: found in saliva?

    • A. amylase (a carbohydrase)
    • B. protease
    • C. lipase

  4. Question 4

    Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 7 min 30 °C: 4 min 40 °C: 9 min 50 °C: 8 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C?

    Answer°C

  5. Question 5

    Why must large food molecules such as starch be digested?

    • A. They are too big to pass through the gut wall into the blood
    • B. They contain no energy
    • C. They are poisonous
    • D. They taste bad

  6. Question 6

    Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 12 min 30 °C: 7 min 40 °C: 3 min 50 °C: 6 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C?

    Answer°C

  7. Question 7

    Which enzyme is described here: breaks starch down into sugars?

    • A. amylase (a carbohydrase)
    • B. protease
    • C. lipase

  8. Question 8

    Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 12 min 30 °C: 8 min 40 °C: 2 min 50 °C: 7 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C?

    Answer°C

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Answer key: Digestive enzymes and the molecules they make

  1. 1. 30 °C

  2. 2. B. Amylase in saliva breaks starch into sugar

  3. 3. A. amylase (a carbohydrase)

  4. 4. 30 °C

  5. 5. A. They are too big to pass through the gut wall into the blood

  6. 6. 40 °C

  7. 7. A. amylase (a carbohydrase)

  8. 8. 40 °C