England · Particle model of matter · Unit PM-U1

Density and states

A proposed unit with 2 lectures, independent practice and a unit assessment.

Unit scope

Filters show lectures with relevant core content. Mixed lectures retain clearly labelled Higher/separate extensions; those extensions are not required on other routes. Difficulty is a design rating, not a GCSE grade.

Lectures

PM-U1 · Density and states

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PM-01 · PM-U1 · Planned

Density and particle arrangements

  • ScopeShared
  • Difficulty2 / 4 · proposed
  • Time25–30 min · estimated
  • StatusPlanned

Learning objectives

Calculate density and explain state differences using arrangements/separations without changing particle size.

8463 §§4.3.1.1 / 8464 §§6.3.1.1

DfE single-science pp.42–43 / Combined pp.35. Evidence checked 30 September–1 October 2026. Skills: WS1.2,4.5; MS3b,3c,5c.

Needs firstP0

Explanation

Density compares mass with occupied volume. State models describe particle arrangements and spacing; changes in bulk density need not mean particles change size. A large object can have low density even if its total mass is high.

Concepts, equations and units: ρ=m/V; kg/m³; mass kg, volume m³; solid/liquid/gas models.

Prediction, demonstration and game exercise

Predict, observe, explain

Compare equal-volume solids and equal-mass objects; reveal annotated particle spacing.

Planned learner game exercise

Choose a material for a target mass/volume and classify three particle diagrams.

Independent practice

Three density problems with cm³ conversions and a model limitation explanation.

Original practice example · Shared

A sample has mass 0.20 kg and volume 0.00010 m³. Find density.

Show working and model answer

Working / reasoning

ρ = m/V = 0.20/0.00010.

Answer

2000 kg/m³.

Exit check and success criteria

Two correct calculations with units and correct three state diagrams.

During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.

Misconceptions, practical links and mastery

Check these misconceptions

Particles expand when material expands; denser always means larger particles; density and mass are identical.

Practical preparation

Preparation for RP-P5/RP-C17, AT1.

Virtual preparation and revision only. Required hands-on activities and school records remain separate.

Proposed mastery

0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.

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PM-02 · PM-U1 · Planned

Measuring density: solids and liquids

  • ScopeShared
  • Difficulty3 / 4 · proposed
  • Time35–40 min · estimated
  • StatusPlanned

Learning objectives

Select methods for regular solids, irregular solids and liquids; evaluate volume/mass errors.

8463 §§4.3.1.1;8.2.5 / 8464 §§6.3.1.1;10.2.17

DfE single-science pp.42–43 / Combined pp.35. Evidence checked 30 September–1 October 2026. Skills: WS2.3–2.7,3.4,3.7; MS2a,2b,3c,5c.

Needs firstPM-01

Explanation

Regular solids can use dimensions; irregular solids can use displaced volume if the method is suitable. A liquid needs its mass without the container and a measured volume. Tare, meniscus and trapped-air errors affect the result.

Concepts, equations and units: ρ=m/V; cube/cuboid volume from lengths; displacement volume; tare/subtraction for liquid mass; kg/m³ or g/cm³ converted explicitly.

Prediction, demonstration and game exercise

Predict, observe, explain

Use balance, ruler and displacement vessel; show meniscus/parallax and trapped air errors.

Planned learner game exercise

Measure all three sample types virtually; reject unsuitable methods and collect repeats.

Independent practice

Three density estimates, uncertainty comparisons and a method improvement.

Original practice example · Shared

A container weighs 50 g empty and 130 g with 100 cm³ of liquid. Find liquid density.

Show working and model answer

Working / reasoning

Liquid mass = 130 − 50 = 80 g; ρ = 80/100 = 0.80 g/cm³.

Answer

0.80 g/cm³, equivalent to 800 kg/m³.

Exit check and success criteria

Correct methods for every sample type plus two valid densities and one quantified uncertainty estimate.

During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.

Misconceptions, practical links and mastery

Check these misconceptions

Liquid density uses container mass; displacement volume is total water volume; repeat readings correct a mis-zeroed balance.

Practical preparation

RP-P5/RP-C17; regular/irregular solids and liquids; AT1.

Virtual preparation and revision only. Required hands-on activities and school records remain separate.

Proposed mastery

0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.

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Area capstone

Sources and full programme

Sources checked 30 September–1 October 2026. Specifications govern content; textbooks supplement it. England has no single prescribed Physics course book. The full planning document includes sourced comparisons of Collins separate Physics and Trilogy books, Hodder/Hachette Physics and Oxford Physics listings, with access/approval limitations.

Download the complete Markdown programme and coverage matrix

A subsection map is proposed coverage. Clause-level educator review, item moderation, model validation and hands-on provision remain release gates. No all-board alignment or exam-board endorsement is claimed.