Expansion and Contraction

Grade Level:

7

Duration:

60 minutes

Class Size:

30 students

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Curriculum Alignment - Alberta Science 7

Specific Learning Outcomes (SLOs):

• Physical Science Unit (PS7)
  • PS7.1: Demonstrate an understanding that changes in temperature cause materials to expand (dilate) or contract, and this affects solids, liquids, and gases differently.
  • PS7.2: Investigate and explain predictable patterns of matter in response to temperature changes.

Competencies Addressed:

• Scientific inquiry and problem solving
• Communication of scientific ideas
• Understanding and applying scientific concepts

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Lesson Objectives

By the end of the lesson, students will be able to:

• I can explain how matter changes volume when temperature changes due to expansion and contraction.
• I can describe how solids, liquids, and gases respond differently to temperature changes.
• I can observe and interpret a demonstration illustrating the expansion of gases when heated.

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Success Criteria

Students will be successful if they:

• Clearly explain in their own words the difference between expansion and contraction.
• Describe at least one example of expansion or contraction in solids, liquids, and gases.
• Answer oral questions correctly regarding the concept of thermal expansion.
• Complete the written activity sheet with accurate responses demonstrating understanding.

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Materials Needed

• Balloon
• Hot water container (warm but safe to touch)
• Ice water container
• Transparent bottle or flask
• Worksheets (activity sheet with questions)
• Whiteboard and markers
• Dyslexia-friendly reading materials summarising the concepts
• Enlarged visual posters illustrating expansion and contraction in different states of matter

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Lesson Plan Outline

1. Introduction & Predictive Discussion (10 minutes)

Purpose: Activate prior knowledge and stimulate curiosity.

• Begin by asking: "What do you think happens to a balloon when it is placed near a heat source? Why?"
• Record students' predictions on the board.
• Discuss briefly how temperature affects matter without giving answers yet.

Differentiation:

• Provide sentence starters for ELL and students with language difficulties (e.g., "When temperature goes up, matter...").
• Use visuals showing particles in solids, liquids, and gases to support understanding.

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2. Demonstration: Balloon Heating (15 minutes)

Activity:

• Place a deflated balloon over the mouth of a transparent bottle.
• Place the bottle in warm water and observe.
• Remove and place in ice water, observe contraction.
• Discuss observations highlighting expansion when heated and contraction when cooled.

Scientific Explanation:

• Explain how air particles inside the balloon move faster and take up more space when heated, causing expansion. When cooled, particles slow down and contract.

Question prompts:

• What happened to the balloon when it was heated?
• Why did it change size?
• Does this happen to solids and liquids too? How might it be different?

Differentiation:

• Allow students with sensory sensitivities to observe from a distance or watch a video recording of the demonstration.
• Use clear, dyslexia-friendly fonts on posters and worksheets to reinforce content.

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3. Mini Lecture & Group Discussion (15 minutes)

Content:

• Explain the concepts of dilatation (expansion) and contraction with everyday examples:
  • Solid: Expansion of railway tracks in summer.
  • Liquid: Mercury in a thermometer rising as temperature increases.
  • Gas: Balloon inflation when heated.

I can statement: I can describe how solids, liquids, and gases expand and contract differently when heated or cooled.

Group Activity:

• Students work in small groups and brainstorm additional examples of expansion and contraction for each state of matter.
• Share ideas briefly with the whole class.

Differentiation:

• Provide sentence frames to support group sharing.
• Buddy system pairing for students needing extra support.

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4. Written Activity (15 minutes)

Activity:

• Distribute a worksheet with:
  • Matching terms (dilatation, contraction, solids, liquids, gases).
  • Short answer questions relating to the demonstration and mini lecture.
  • Diagram labelling showing expansion of gas particles.

Extension for advanced learners:

• Challenge advanced students to explain why expansion varies among solids, liquids, and gases using particle theory.

Assessment:

• Use this worksheet as formative assessment of understanding.

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5. Oral Review and Closing (5 minutes)

• Conduct a quick oral quiz with questions like:

  • What is dilatation?
  • Give an example of contraction in everyday life.
  • Why do gases expand more than solids when heated?

• Review initial board predictions and discuss any changes in thinking.

Reflection:

• Have students write a short “I can…” statement reflecting what they learned today.

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Differentiation Strategies Summary

Learner Type	Strategy
ELL & struggling readers	Sentence frames, visuals, verbal explanations
Dyslexic students	Dyslexia-friendly fonts/materials, verbal instructions, clear layouts
Sensory-sensitive	Options to observe remotely or via videos
Advanced learners	Extension questions requiring deeper particle theory explanation
Students needing extra practice	Partner/buddy system, extra scaffolding during group work

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Assessment Overview

Assessment Type	Purpose	Detail
Oral Questions	Check understanding during lesson	In-class questions during demo and review
Written Worksheet	Formative summative check	Matching, short response, diagram labelling
Student Reflection	Self-assessment of learning	Written “I can…” statement at lesson end

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This lesson integrates inquiry, hands-on demonstration, reflective discussion, and written assessment to foster conceptual understanding of thermal expansion and contraction as per Alberta Science 7 standards. It incorporates varied teaching strategies ensuring accessibility and challenge appropriate for 7th graders while keeping the content relevant and engaging.