Matter Transformations

Overview

In this lesson, students explain how thermal energy changes matter between states and how measurable properties help us classify states of matter. The focus links to the idea that all matter is made of atoms and that changes of state are observable, measurable, and can be modelled.

Learning intentions

• WALT describe the states of matter using defining properties: shape, mass, and volume.
• WALT explain how adding or removing thermal energy causes changes of state (melting, freezing, evaporation, condensation, sublimation, deposition).
• WALT use evidence from observations and measurements to support scientific explanations.
• WALT create and interpret a simple particle model to represent changes of state.

Success criteria

• I can classify common materials as solids, liquids, or gases using shape, mass, and volume.
• I can describe what happens during a change of state and link it to thermal energy being added or removed.
• I can support my explanation with data (for example temperature/volume/time/observations).
• I can use a particle model to match the state of matter before and after a change.

Curriculum links

• Science (Matter / Elements, molecules, and compounds): matter is composed of atoms.
• Physical Science (States of matter): classifying materials using shape, mass, and volume.
• Physical Science (States of matter): explaining state changes using measurable, observable evidence (including the role of thermal energy).
• Science capabilities: using scientific language and communicating findings; interpreting evidence and making claims.

Lesson structure (60 minutes)

1. 0–7 min · Hook: “What state is it?” demo

• Teacher shows three sealed containers labelled only A, B, C containing ice water, liquid water, and water vapour (or dry ice in a safe setup if available).
• Students do a quick write: “Which container is solid/liquid/gas? What evidence would convince you?”

2. 7–18 min · Mini-teach: properties that define states

• Teacher displays a table: shape, mass, volume; guides students through examples (ice, liquid water, steam/air).
• Students complete a “Think–Pair–Share” fill-in: for each state, they write what happens to shape and volume and how mass behaves (stays the same unless matter is lost).

3. 18–30 min · Investigation: measure and observe a phase change

• Teacher runs a short rotation or teacher-led demo: heating/monitoring a small amount of water in a clear container (or melting ice) using a thermometer; students record temperature over time and observations of appearance.
• Students record: initial state, time intervals, temperature changes, and what they observe (e.g., melting begins, liquid forms, steam forms if feasible); they keep mass measurements if the setup allows (or use “mass is conserved” claim with justification if not).
• Note: If full boiling to vapour isn’t possible, focus on melting and heating within the available timeframe.

4. 30–42 min · Model: particle explanation of change of state

• Teacher provides particle diagram cards (solid particles tightly packed; liquid particles close with movement; gas particles far apart).
• Students in groups sequence cards to match the observed change (for example: solid → liquid during melting; liquid → gas during evaporation/boiling if demonstrated). They then write a 3-sentence explanation using: “When thermal energy is added/removed, particles…”
• Teacher circulates to check that explanations link thermal energy to changes, not just “temperature changes.”

5. 42–52 min · Evidence talk: claim–evidence–reasoning

• Teacher prompts a structured discussion: “What evidence shows a change of state happened?” and “Why does mass stay the same in a closed system?”
• Students complete a CER paragraph: Claim (state before/after), Evidence (at least one measurement/observation), Reasoning (use particle + thermal energy idea).

6. 52–60 min · Exit ticket: quick assessment

• Teacher gives a short prompt: “A puddle dries on a warm day. Explain what changes and which direction thermal energy moves (added/removed).”
• Students answer using one diagram or labelled particle description and one measurable-observable evidence point from their notes/demonstration.

Resources

• Clear container(s), thermometer or temperature probe, ruler/marking pen for volume levels (or measuring cylinder if available)
• Small quantities of water and ice (or dry ice only if school safety procedures allow)
• Heat source (hot plate/benchtop heater) or water bath setup; heatproof mat and tongs
• Safety goggles for all students; heat-resistant gloves for teacher handling
• Data recording sheets (temperature vs time table + observation prompts)
• Particle model cards and answer templates for CER
• Exit ticket slips and pens
• Projected slide or board diagram showing shape/mass/volume for states

Assessment

• Formative: teacher checks group particle models for correct linking of state to particle arrangement and thermal energy direction.
• Formative: review investigation data tables for accurate recording of observations and temperature trends.
• Summative (exit ticket): evaluate whether students explain state change with thermal energy and reference observable/measurable evidence; check correct use of shape, mass, and volume language.

Differentiation

• Support: provide sentence starters for CER (e.g., “My claim is…”, “The evidence is…”, “This happened because…”).
• Support: offer partially completed state-property charts and particle diagrams with word banks (solid, liquid, gas; thermal energy; melting/evaporation).
• Extension: ask students to compare two scenarios (same temperature change but different starting states) and predict which change of state would occur first.
• EAL/SEN: allow verbal rehearsal before writing; use visuals and consistent key terms; accept diagrams as part of explanations.