Exercises: Material selection

Four samples of common workshop materials are presented, numbered from 1 to 4:

1. A light-toned strip of wood with visible natural grain.

2. A shiny reddish metal sheet.

3. A rigid, colorless, transparent sheet.

4. A dark gray, heavy, magnetic metal bar.

Identify them and suggest an object you could make with each one, justifying your choice with a property of the material.

Define in your own words and give an example of each of these material properties: hardness, electrical conductivity, and density.

Match each object with the property of the material that makes it possible: (a) a window, (b) a copper wire, (c) a hammer, (d) a raincoat. Properties: conductivity, hardness, waterproofing, and transparency. Justify each pair in one sentence.

Classify these objects according to their main material (wood, metal, plastic, ceramic, or textile): a frying pan, a plant pot, a T-shirt, a transparent ruler, and a pencil.

Explain the difference between a mechanical property (such as hardness or elasticity) and a thermal or electrical property (such as conductivity), with an example of each type.

What property makes cork a good bottle stopper and rubber a good material for tyres? Name the property in each case and explain it in one sentence.

State whether these statements are true or false and correct the false ones: (a) all metals are attracted to a magnet, (b) glass is an electrical insulator, (c) dry wood conducts electricity well.

Name an everyday object made from recycled or clearly recyclable material and explain the advantage of choosing it.

To build a garden bench that will always be outdoors, compare wood and steel across at least three relevant properties and decide which you would choose, justifying your decision.

The graph compares the density of three workshop materials. For a school drone frame, it needs to be as lightweight as possible while remaining rigid. Using the data in the graph, explain which material you would choose and what other property you would check before deciding.

The handles of pots and frying pans are made of plastic or wood, never the same metal as the body. Explain this design decision using at least two material properties.

The handle of a screwdriver combines hard plastic with rubberised areas. Explain what properties each material provides and why the handle is not made entirely of steel like the shaft.

The same chair can be made from pine, steel, or polypropylene. Create a comparison table with three relevant properties and decide which you would choose for a school canteen, justifying your choice.

Explain what a composite material is using the example of reinforced concrete or fibreglass: what each component provides and why the combination improves upon the materials separately.

A team chooses aluminium for an outdoor structure 'because it does not rust'. Qualify this statement: what actually happens to aluminium when exposed to air and why that ultimately protects it.

Choose a material for each of these items and justify it with a key property, also ruling out an alternative that seems valid: the bottom of an aquarium, a fridge magnet, and the handle of a kettle.

A material must be chosen for a reusable bottle for a school bag. Evaluate stainless steel, plastic, and glass based on weight, impact resistance, hygiene, and cost; choose one and justify your decision, acknowledging which disadvantages you accept.

The plastic hinges on a locker break after a few months of use. Analyse which property was ignored when choosing that material, what alternative material you would propose, and why.

A solar garden light has several parts: the post, the solar panel housing, the shade protecting the light, and the internal battery holder. Choose a specific material for each part and justify each choice using a property.

A child's toy must be non-toxic, bite-resistant, washable, and lightweight. Analyse which materials would meet all the requirements and what trade-offs each possible option involves.

Investigate what Corten steel is and why it is used in unpainted outdoor sculptures. Relate it to the idea of a "protective layer" and compare it with the solution of painting steel every few years.

A yoghurt pot combines several materials (plastic pot, aluminium lid, label). Analyse why the use of multiple materials complicates its recycling and propose a redesign that avoids it.

Design a simple workshop experiment to compare the hardness of three materials (pine wood, plastic and aluminium): procedure, which variable is measured and how to ensure the comparison is fair.

Evaluate the "bioplastic versus recycled plastic" dilemma for manufacturing a bottle: raw material origin, degradation and recyclability. Defend one option while acknowledging its weaknesses.