Water Functions

Overview

In this lesson, students explore the chemical nature of water and how its properties support key biological roles in the human body. They will link structure and behaviour to bodily functions, meeting the goal of describing at least three water-dependent processes.

Learning intentions

• Students will describe water as a simple molecule with polar properties and explain why it dissolves many substances.
• Students will explain how water supports transport of materials in the body.
• Students will identify at least three biological functions that depend on water.
• Students will use scientific vocabulary to justify their explanations clearly.

Success criteria

• I can describe water’s polar nature and relate it to why water dissolves substances.
• I can name at least three bodily functions that require water (e.g., temperature control, transport, digestion/absorption).
• I can explain how water contributes to each function using clear, accurate reasoning.
• I can communicate my ideas in a structured paragraph or model.

Curriculum links

• Science: understanding that materials have physical and chemical properties and that these link to biological processes.
• Science: applying knowledge of molecules/materials to explain real-world biological systems (food and nutrition).
• Science: using scientific language to describe processes and make reasoned links between causes and effects.

Lesson structure (60 minutes)

1. 5 min — Starter: “Why water?”

• Students list quick reasons water matters to the body (any three). Provide sentence starters: “Water is important because…” and “One job water does is…”

2. 10 min — Mini-teach: Water’s chemical nature

• Show or describe water molecules (no need for complex equations): discuss that water is polar and forms hydrogen bonds.
• Use a dyslexia-friendly approach: provide a short, printed summary with large font and allow audio reading of key lines by the teacher (or student reading with support).

3. 15 min — Model task: Properties to functions

• In pairs, students match water properties to body roles on prepared cards (property → consequence → body function).
• Target roles:
• Temperature control (sweating and evaporation),
• Transport of substances (blood plasma, moving nutrients and wastes),
• Digestion/absorption (water in saliva and digestive processes),
• Waste removal (urine and hydration of tissues),
• Lubrication and protection (joint fluid, mucus).
• Students must write one-sentence justification for each match.

4. 10 min — Whole-class discussion: Build “Function Chains”

• Choose 2–3 chains and refine them together: Property → mechanism → bodily effect → outcome for health.
• Teacher emphasises “because” reasoning and scientific vocabulary (polar, dissolve, transport, regulate, lubricate, temperature, hydration).

5. 10 min — Assessment activity: Exit-brief (success criteria check)

• Individually, students produce a short response answering: “Describe at least three bodily functions that depend on water. For each, explain how water contributes.”
• Provide a scaffold: bullet prompts and a required structure (Function + Where it happens + How water helps).

6. 5 min — Peer check: Two Stars and a Step

• Students swap work and highlight:
• Two functions they can clearly identify,
• One step to improve clarity (e.g., add a “because” explanation, include a mechanism, or correct wording).

7. 5 min — Plenary: Quick confidence rating

• Students show a small card rating (1–5) for confidence in explaining water’s role in three body functions.
• Teacher collects common misconceptions for next lesson.

Resources

• Pre-prepared “property → consequence → body function” card set (laminated or printed)
• Dyslexia-friendly one-page mini summary of water’s polar nature and hydrogen bonding (large font, short lines)
• Sentence starters and paragraph scaffold template for the exit-brief
• Highlighter pens or sticky notes for peer feedback (“Two Stars and a Step”)
• Timer for timed tasks
• Slides or teacher notes with simple diagrams of water polarity and hydrogen bonding (optional)
• Individual exit-brief sheets (at least 10)
• Large-print word bank (polar, dissolve, transport, regulate, lubricate, hydration, digestion)

Assessment

• Formative: observe pair matching accuracy and check justifications during property-to-function task.
• Summative-in-class: exit-brief response assessed against success criteria (three functions plus mechanism-based explanation).
• Peer assessment: use “Two Stars and a Step” to confirm understanding and target next improvement.

Differentiation

• Support:
• Provide sentence starters and the scaffold for the exit-brief.
• Use smaller card sets (fewer options) for students who need less choice during matching.
• Offer audio support for the mini summary and allow partner reading.
• Extension:
• Students add an extra “function chain” beyond the three required and include an example of how dehydration could affect each function.
• Students explain one function using two separate mechanisms (e.g., transport plus waste removal).
• EAL:
• Provide a word bank with simple definitions and example phrases (“Water dissolves…”, “Water helps transport…”).
• Encourage students to rehearse a short explanation with a partner before writing.
• SEN (including dyslexia):
• Keep reading load low: fewer lines per sheet, clear headings, and allow verbal responses if needed (record teacher notes for assessment).
• Provide exemplars of what a strong function explanation looks like.

Extension (optional)

• Ask advanced learners to link water’s properties to one common misconception (e.g., “detox water”) and explain, scientifically, what water actually contributes to bodily processes.