Science · Grade 3 · Matter and Its Properties · Term 2

Designing with Materials

Students will apply their understanding of material properties to design and build a simple structure or object for a specific purpose.

• Ontario Curriculum Expectations
• 3-5-ETS1-1

About This Topic

Designing with Materials guides students to select and combine materials based on properties like strength, flexibility, absorbency, and buoyancy to build simple structures or objects for specific purposes. For example, they might construct a bridge to span a gap and support weight or a waterproof shelter. Students justify choices by explaining how properties match the problem, then test and refine designs through the engineering process: plan, build, test, improve.

This topic connects the Matter and Its Properties unit to engineering standards, such as 3-5-ETS1-1. It builds skills in problem-solving, evidence-based decisions, and critique as students evaluate peers' work against criteria like stability or functionality. Observations from earlier material tests inform designs, reinforcing scientific inquiry.

Active learning shines here because students gain direct experience with cause and effect. Constructing and testing reveals how properties predict performance, while failures prompt iteration and resilience. Collaborative building fosters communication and shared reasoning, making concepts stick through real-world application.

Key Questions

1. Justify the selection of specific materials for a design project.
2. Critique the effectiveness of a design based on the properties of its materials.
3. Construct a solution to a problem using appropriate materials and tools.

Learning Objectives

• Design a simple structure, such as a bridge or shelter, that meets specific criteria for strength or weather resistance.
• Justify the selection of at least three materials for a design project by explaining how their properties (e.g., strength, flexibility, absorbency) address the project's purpose.
• Critique the effectiveness of a peer's design based on its stability, functionality, and the appropriateness of the materials used.

Before You Start

Properties of Objects

Why: Students need to have identified and described basic properties of various materials before they can select them for a specific purpose.

Sorting Objects by Properties

Why: This prior learning helps students categorize materials based on characteristics like hardness, flexibility, or absorbency, which is fundamental to making informed design choices.

Key Vocabulary

property	A characteristic of a material, such as strength, flexibility, or absorbency, that describes what it is like and how it behaves.
strength	The ability of a material to withstand force without breaking or deforming. Strong materials can hold more weight or resist impact better.
flexibility	The ability of a material to bend or change shape without breaking. Flexible materials can be easily molded or shaped.
absorbency	The ability of a material to soak up liquids. Absorbent materials can hold water or other fluids within them.
buoyancy	The ability of an object to float in a liquid. Buoyant materials are less dense than the liquid they are in.

Watch Out for These Misconceptions

Common Misconception

Heavier materials always make stronger structures.

What to Teach Instead

Strength depends on the purpose and properties like flexibility or rigidity, not just weight. Hands-on testing shows lightweight straws outperform heavy clay in bridges. Group critiques help students articulate why specific properties matter.

Common Misconception

All plastics have the same properties.

What to Teach Instead

Plastics vary in flexibility, waterproofing, and durability. Experiments with different types during building reveal distinctions. Peer testing and discussion correct overgeneralizations by linking observations to design outcomes.

Common Misconception

Designs work perfectly on the first try.

What to Teach Instead

Iteration is key; initial failures teach property limits. Active redesign cycles build understanding that testing informs improvements. Student-led reflections reinforce the engineering process.

Active Learning Ideas

Engineering Challenge: Paper Bridges

Provide paper, straws, tape, and string. Groups define a problem like spanning a 20 cm gap to hold 20 pennies. They sketch plans, justify material choices by properties, build, test with weights, and improve based on failures. Share results in a class gallery walk.

45 min·Small Groups

Design Lab: Floating Boats

Supply recyclables like foam, corks, foil, and clay. Pairs design boats to carry a cargo of 10 pennies without sinking. Test in water trays, record property observations, then redesign for better buoyancy. Discuss successes as a class.

35 min·Pairs

Stations Rotation: Material Towers

Set up stations with popsicle sticks, marshmallows, blocks, and straws. Small groups build 30 cm towers at each, testing stability with a fan or shake table. Rotate stations, compare properties, and vote on strongest design per material set.

50 min·Small Groups

Whole Class: Shelter Build-Off

Pose a problem: build a shelter for a toy figure against dripping water. Class brainstorms criteria, then individuals select materials and construct. Test with spray bottles, critique in pairs, and revise before final showcase.

40 min·Individual

Real-World Connections

• Architects and engineers select specific materials like steel, concrete, and glass for skyscrapers based on their strength, durability, and resistance to weather. They must choose materials that can support immense weight and withstand wind and seismic activity.
• Product designers choose materials for everyday items, such as clothing or containers, based on properties like absorbency for towels or flexibility and durability for a backpack. These choices directly impact how well the product functions for its intended use.
• Construction workers choose different types of wood, plastic, or metal for building houses or furniture, considering factors like strength for structural beams, flexibility for trim, and water resistance for outdoor elements.

Assessment Ideas

Exit Ticket

Provide students with a scenario, e.g., 'Design a small raft to hold a toy figure in water.' Ask them to list two materials they would use and explain why each material's property is suitable for the raft's purpose.

Peer Assessment

After students build their designs, have them present their object to a small group. Provide a simple checklist: 'Does the design meet the purpose?' 'Are the materials appropriate?' 'What is one thing that works well?' 'What is one suggestion for improvement?'

Quick Check

During the building phase, circulate and ask students questions like, 'Why did you choose this material for this part of your design?' or 'What property of this material makes it a good choice for holding weight?'

Frequently Asked Questions

How do I scaffold the engineering design process for grade 3?

Start with a clear problem statement and criteria checklist. Model planning with think-alouds, provide material property charts from prior lessons, and use rubrics for testing. Peer feedback stations after builds encourage critique. This structure supports justification and iteration without overwhelming students, typically spanning 2-3 lessons.

What everyday materials work best for designing with properties?

Use recyclables like straws for flexibility, foil for waterproofing, popsicle sticks for rigidity, and sponges for absorbency. These mimic real-world options and tie to matter properties. Pre-test with class demos to build familiarity, ensuring safe, accessible supplies that spark creativity and cost little.

How can active learning help students apply material properties to designs?

Active approaches like building and crash-testing structures let students see properties in action, such as why rigid sticks beat soft clay for towers. Collaborative rotations and redesigns turn failures into learning moments, deepening justification skills. Data logs from tests connect observations to choices, far beyond worksheets, fostering ownership and retention.

How should I assess student designs in this topic?

Use a rubric covering justification of materials (e.g., 'Explains flexibility need'), functionality via tests, and improvement reflections. Portfolios with sketches, photos, and peer critiques provide evidence. Self-assessments on 'What property surprised me?' reveal understanding. Align to key questions for Ontario curriculum standards.