States of Matter Sort

Overview

This is lesson 8 of 8 in Exploring States of Matter. Students use particle models to classify unusual materials (especially gloop/oobleck) and explain why some materials don’t fit neatly as only solids or only liquids.

Learning intentions

• Students will apply models of particles and motion to explain observable properties of solids and liquids (and where gloop fits differently).
• Students will classify gloop and other unusual samples using evidence from observations.
• Students will plan and carry out a short, repeatable investigation to support classification.
• Students will compare findings with peers and identify possible sources of error.

Success criteria

Students can…

• I can describe what happens to gloop when it is pushed, stretched, or left to settle.
• I can explain gloop’s behaviour using particle motion and arrangement ideas.
• I can classify a material as solid-like, liquid-like, or “not clearly one or the other” using evidence.
• I can record observations and use them to justify a reasoned conclusion.

Curriculum links

• AC9S5U04: explain observable properties of solids, liquids and gases by modelling the motion and arrangement of particles.
• AC9S5I01: pose investigable questions to identify patterns and make reasoned predictions about how materials behave.
• AC9S5I02: plan and conduct a repeatable investigation, deciding variables, measuring, controlling, and using equipment safely.
• AC9S5I03: use equipment to observe, measure and record data with reasonable precision (tables, diagrams, or digital recording).
• AC9S5I05: compare methods and findings with others, recognise possible sources of error, and draw reasoned conclusions.

Lesson structure (80 minutes)

1. 0–10 min · Hook and focus question. Teacher shows a prepared sample of gloop and briefly demonstrates “slow squeeze” vs “quick push” behaviour; students record the first observable effects in notebooks. Students answer: “What kind of material is this—solid, liquid, or something else? Why?”

2. 10–25 min · Direct teach: particle model for “odd” behaviour. Teacher revisits particle ideas: solids have particles arranged closely with limited movement; liquids flow because particles slide past each other. Then teacher connects gloop’s behaviour to particle model language: the material can act solid-like under fast force and flow like a liquid under gentle force. Students complete a guided particle diagram for “gently poured gloop” and “pushed gloop,” using sentence starters.

3. 25–35 min · Set up the investigation (repeatable). Teacher introduces a short investigation with two tests per material (gloop and one additional “unusual” sample such as slime, gel, or a thick fluid from teacher collection). Safety reminder: gloves if needed, wipe spills immediately, no tasting, handle containers carefully. Students, in groups, write a simple method: what they will change (force/handling speed), what they will measure/record (time to settle, behaviour description, whether it flows), and what they will control (same container size, same amount, same test tool).

4. 35–55 min · Guided investigations: classify with evidence. Teacher circulates, checks for fair-test decisions, and prompts groups to record observations using the class observation sheet. Students perform tests:

• Test A: “gentle tilt/pour” (observe flow and settling)
• Test B: “quick push/impact” (observe resistance and shape change) They record evidence with clear words and quick sketches, then decide where each sample belongs: solid-like, liquid-like, or “not clearly one or the other” with a justification.

5. 55–65 min · Compare and reason together. Teacher leads a class gallery walk or structured share: each group states their classification and one key piece of evidence, then one possible error source (e.g., different force strength, different sample amount, uneven mixing). Students use the sentence frame: “Our evidence shows… therefore we conclude… a possible error is…”

6. 65–75 min · Reflection: link back to observable properties. Teacher asks students to complete a short exit-style reflection: “How do particle motion/arrangement explain why gloop doesn’t fit only one category?” Students write 4–5 sentences and ensure they reference at least two observable behaviours from their investigation.

7. 75–80 min · Clean-up and quick teacher check. Teacher checks observation sheets for completeness and briefly reviews common misconceptions. Students clean equipment, wipe benches, and return materials.

Resources

• Gloop/oobleck samples (prepared and portioned), trays or containers for each group
• One additional unusual material per group (e.g., slime/gel/thick gel-like sample) in labelled containers
• Gloves (optional), paper towels, bin liners for waste
• Observation recording sheet (two tests + classification box + evidence lines)
• Sentence starters and particle model templates
• Rulers or measuring spoons/cups for consistent sample amounts
• Stopwatch/timer (phone-free if required by school policy)
• Whiteboard/markers, student notebooks

Assessment

• Formative: teacher observations during investigations (fair test planning, safe handling, evidence recording).
• Formative: check particle model diagrams and classification justifications against success criteria.
• Exit reflection: 4–5 sentence response linking particle ideas to gloop’s observable behaviours.

Differentiation

• Guided observation sheets with pre-filled headings (Test A, Test B, Evidence, Classification, Reason).
• Vocabulary support cards: solid, liquid, flow, particles, arrangement, motion, resistance, settle, evidence, conclude.
• Sentence starters for reasoning: “When we… it shows… because…”
• For students needing more support, provide a partially completed classification paragraph and a simplified particle diagram with arrows already drawn.
• For students ready for more challenge, require an extra “controlled variable” statement (what they kept the same).

Extension

• Students research (teacher-provided printed sources or a short curated reading set) a non-Newtonian fluid, such as cornstarch-and-water oobleck variations or other real-world uses, and write a brief paragraph: the behaviour, observable evidence, and one application (e.g., protective gear, materials testing, stage effects).