Disaccharides Focus

Overview

In this lesson, students investigate disaccharides (sucrose, lactose, and maltose) by linking their structures to how they are formed from monosaccharides. They build clear explanations of what bonds form and what products result when disaccharides are broken down.

Learning intentions

• Students will be able to describe disaccharides as pairs of monosaccharides joined together.
• Students will identify sucrose, lactose, and maltose and state which monosaccharides each contains.
• Students will explain how disaccharides form using condensation reactions (water released).
• Students will use scientific diagrams/labels to represent formation and breakdown.

Success criteria

• I can explain, in my own words, how a disaccharide is formed from two monosaccharides.
• I can correctly name the monosaccharides present in sucrose, lactose, and maltose.
• I can draw a labelled structural diagram showing a disaccharide linkage and products.
• I can state that breaking a disaccharide uses hydrolysis and involves water.

Curriculum links

• Understanding of the chemical processes involved in digestion of carbohydrates.
• Using models to represent biological molecules and chemical reactions.
• Using scientific reasoning to link structure to function in food and nutrition.
• Communicating explanations using appropriate scientific vocabulary.

Lesson structure (60 minutes)

1. 5 min – Starter: Quick nutrient recall Students recap last lesson’s monosaccharides (glucose, fructose, galactose) using a short, teacher-led questioning routine. Use a dyslexia-friendly approach: allow students to respond verbally or with short sentence stems rather than only writing.

2. 10 min – Mini input: What makes a disaccharide Teacher explains: disaccharides are formed when two monosaccharides join by a glycosidic bond, typically via condensation, releasing water. Show three focus examples (sucrose, lactose, maltose) and connect each to its component monosaccharides.

3. 10 min – Model-building activity (pair work) In pairs, students use cut-out monosaccharide cards and bond templates to build each disaccharide (one model per pair, rotating after 5 minutes). Students must label: “monosaccharide + monosaccharide” and indicate “condensation: water released.” Teacher circulates with a prompt: “What is joined, what bond forms, and what happens to water?”

4. 10 min – Guided explanation writing Students complete a structured explanation using sentence scaffolds:

• “Sucrose is made from…”
• “A condensation reaction joins…”
• “A glycosidic bond forms, and…”
• “When broken down, hydrolysis uses water to…” Provide dyslexia-friendly reading options: an audio recording of the model explanation and a shortened checklist version on the board.

5. 10 min – Diagram check: Formation vs breakdown Teacher demonstrates two simple diagrams on the board (formation and breakdown). Students then compare their pair models to a “two-step target”:

• Step 1: formation (condensation, water out)
• Step 2: breakdown (hydrolysis, water in) Students mark one improvement for their own work (no red-pen required—use “next action” notes).

6. 10 min – Success-criteria sharing Each pair presents one disaccharide explanation (about 1 minute). Audience members respond using one of two question stems:

• “Your explanation says… Can you add what happens to water?”
• “Can you name the monosaccharides and link them to the bond?”

7. 5 min – Exit ticket Students answer two prompts:

• “Explain how lactose is formed from its monosaccharides.”
• “In hydrolysis, what happens to water and the bond?” Collect for quick formative assessment.

Resources

• Monosaccharide cards (glucose, fructose, galactose) and disaccharide cards (sucrose, lactose, maltose)
• Bond templates and simple diagram paper (blank and pre-labelled versions)
• Sentence stems and checklist for explanation writing
• Audio (teacher-made) recording of a model explanation for access
• Board slides/handout with the three disaccharides and their component monosaccharides
• Coloured pens/pencils (optional) to distinguish monosaccharide units from linkage
• Exit ticket slips (with dyslexia-friendly spacing and short lines)

Assessment

• Formative assessment through teacher observation during model building (correct pairing of monosaccharides and correct condensation language).
• Feedback from the diagram check activity (whether students show water released for formation and water used for hydrolysis).
• Summative check via the exit ticket (clarity of explanation, correct naming, and correct reaction direction for water).

Differentiation

• Support: Provide pre-printed templates with monosaccharide names already placed; allow oral explanations to accompany written work; supply a reduced sentence scaffold version (fewer lines, more prompts).
• Support for SEN/dyslexia: Offer audio playback of the scaffold, larger font handouts, and shorter chunks (one disaccharide model at a time).
• Extension (advanced learners): Ask students to write a “compare and contrast” explanation: how sucrose differs from lactose in component monosaccharides, and how this could affect digestion behaviour in the body (still grounded in structure and reaction type).
• Extension (concept challenge): Students create a general rule statement for disaccharide formation and breakdown, including the role of condensation and hydrolysis, using a consistent template for any two monosaccharides.