Enzymes in Digestion

Overview

In this lesson (Lesson 4 of 24) students build from the previous work on the digestive system by focusing on how enzymes help break down food. Students use a model/investigation-style reasoning to connect enzyme role to specific digestive processes.

Learning intentions

• WALT explain what enzymes do in digestion.
• WALT describe how enzymes break down large food molecules into smaller ones.
• WALT link the idea of “specific tasks” (enzymes matching substances) to digestion outcomes.
• WALT use scientific language to define an enzyme clearly.

Success criteria

• I can define an enzyme in my own words.
• I can explain that enzymes speed up chemical reactions in the body.
• I can give at least two everyday examples of enzymes and relate one to digestion.
• I can use words like “break down”, “chemical reaction”, and “specific” accurately.

Curriculum links

• Organise learning around Organism Diversity / Determining organism traits by explaining how body processes rely on specific molecules with specific roles.
• Biological Science / Digestive system (Practices) by designing and interpreting investigations/models about how enzymes break down food.
• Biological Science / Digestion by explaining how digestion breaks down food for body use.

Lesson structure (55 minutes)

1. 0–5 min · Bell ringer. Teacher displays prompts: “Where have you heard of enzymes? What products use enzymes? What do they do?” Students do a quick think-write, then share one example with a partner.

2. 5–15 min · Whole-class discussion: everyday to body. Teacher charts student ideas (e.g., laundry detergent, toothpastes, meat tenderiser, yoghurt cultures) and asks: “What job do these enzymes perform?” Students contribute ideas; teacher redirects any misconceptions toward the “enzyme as a helper for chemical reactions” idea.

3. 15–25 min · Direct teach: what an enzyme is. Teacher explains: enzymes are large molecules made by cells; they speed up specific chemical reactions; in digestion they help break down food into smaller molecules that the body can use. Students record a short two- or three-sentence summary and underline key words (enzyme, chemical reaction, break down, specific).

4. 25–40 min · Model-based reasoning activity (investigation-style). Teacher sets up a “matching” model: students receive cards showing a substrate (starch/protein/fat) and an enzyme label (e.g., “amylase”, “protease”, “lipase”) plus one “wrong match” card for misconception checking. Students work in groups of 3–4 to:

• choose which enzyme best matches each food type and justify using “specific role” language;
• predict what happens if the wrong enzyme is used (little/no breakdown);
• record one evidence statement from the model. Teacher circulates with prompts: “What does ‘specific’ mean here?” “What does breakdown look like?”

5. 40–48 min · Mini wrap: connecting to digestion. Teacher links student model outcomes back to the digestive system pathway: enzymes act in appropriate parts to progressively break food down. Students do a rapid “turn and tell” to explain one chain: enzyme → breakdown → smaller molecules.

6. 48–55 min · Exit ticket. Teacher hands out an exit ticket with one prompt: “Define ‘enzyme’ in your own words. Include what it does and why it matters for digestion.” Students write independently; teacher collects for quick formative assessment.

Resources

• Printed enzyme “matching” card set (starch/protein/fat + enzyme labels + one incorrect pair)
• Group work worksheets for recording matches and justifications
• Student science notebooks or writing pads
• Exit ticket slips (one per student)
• Projector/board for bell ringer prompts and class idea chart
• Timer to keep groups on task
• Optional: simple diagram handout of digestion showing enzyme action points (no detailed biology beyond purpose)

Assessment

• Formative: teacher listens to bell ringer pair shares for everyday examples and misconceptions.
• Formative: during the model activity, teacher checks group justifications for accurate use of “specific” and “break down” language.
• Summative (micro): exit ticket checked for a clear, accurate definition of “enzyme” in student wording.

Differentiation

• Support: provide sentence starters for the exit ticket (e.g., “An enzyme is a… that…” “It helps the body…” “It matters because…”).
• Support: give a vocabulary word bank on the worksheet (enzyme, chemical reaction, break down, specific, digestion).
• Challenge/extension within task: ask advanced groups to add one prediction about what would happen if enzyme activity were reduced (e.g., digestion slower) and link to “speed up reactions.”
• EAL/SEN: allow drawing + short labels for one recorded justification, then require one full sentence for the exit definition.
• Attention support: assign clear roles in each group (reader, matcher, recorder, reporter).

Extension (optional)

• If time remains, students add a “myth vs science” statement to the class chart (e.g., “Enzymes digest food instantly without chemical reactions” → revise to correct understanding).