Everyday Materials: Properties and Uses

Your pencil is a thing you use to write. Wood is one material in it. An object is a thing. A material is what makes the thing.

Ask two questions

Try this with a metal spoon.

1. Ask, “What is it?” It is a spoon. That names the object.
2. Ask, “What is it made of?” It is made of metal. That names the material.

Now look at a wooden chair. “Chair” tells you the object. “Wood” tells you its material. If someone asks what the chair is made of, answer “wood.”

A material name tells more than a color or shape. “Red” describes a ball, but it does not name its material. A red ball could be rubber, plastic, or wool.

Look at each part

One object can have several materials. Look at a window. The clear pane is glass. Its frame can be wood, metal, or plastic. You need to look at both parts to name its materials.

A pencil has even more parts. Wood wraps around a dark gray core. The core is graphite mixed with clay. People often call it “lead,” but it is not the metal lead. Some pencils also have a metal band and a rubber or plastic eraser.

You can describe the parts one at a time: “The outside is wood. The band is metal.” You do not have to pick just one material for the whole pencil.

Match names in different ways

Put a wooden spoon beside a metal spoon. Both objects are spoons. Their materials are different. A plastic spoon would make a third example.

Now think about a wooden spoon and a wooden door. The objects are different, but they share a material. Wood can also make tables, fences, and toy blocks.

Watch the word “glass.” “A glass” can mean a drinking object. “Glass” also names a material. A clear plastic cup is made of plastic, even though you can see through it.

You meet wood, plastic, glass, metal, rock, paper, and fabric every day. Use how they look and feel to help name them.

Hard materials around you

Wood comes from trees. It is usually hard and strong. Look for lines called the grain in a wooden door or block.

Metal is usually hard and strong too. Clean metal is often shiny. Steel, aluminum, copper, and gold are metals. A metal key can feel heavy for its size. Thin aluminum foil is light and easy to bend.

Glass is hard and smooth. Window glass is see-through, and glass keeps water out. It can break into sharp pieces. If glass breaks, leave it alone and tell an adult.

Rock comes from the ground. Most rock is hard and heavy. Granite, slate, marble, and chalk are kinds of rock. Rock cut for building is often called stone. You might see stone steps or a slate roof.

Thin, soft, or bendy materials

Paper is thin, light, and bendy. Many kinds soak up water and tear easily. Books and tissues use paper. Cardboard is thicker, stiffer paper used for boxes.

Fabric, or cloth, is made from tiny strands called fibers. Cotton, wool, and polyester are fibers. People spin fibers into threads, then weave or knit many fabrics. Felt is made by pressing fibers together until they tangle. Fabric usually folds easily. It makes shirts, towels, and curtains.

Plastic comes in many forms. A toy brick is hard and stiff. A plastic bag is thin and bendy. Both are plastic. Plastic is usually light and waterproof.

Rubber is stretchy and bouncy. You find it in bands, balls, boots, and tires. You also meet clay for shaping and brick for building. Water is a material too: it is what fills your water bottle.

Put clues together

Suppose you find a clear bottle. You can see through it. Does that mean it is glass? No: some plastic is clear too.

Look for more clues. Does the bottle bend gently? Does it feel light for its size? Those clues can help you recognize plastic. A shiny surface alone does not mean metal either. Some wrapping paper is shiny.

Gently tapping a metal spoon makes a ringing “ting.” A plastic spoon makes a duller click. Looking, feeling, and listening together tell you more than one clue.

Materials have starting places. Some come from plants or animals. Others come from the ground. People change some of these into new materials.

Find natural materials

A natural material comes from nature.

Water is natural too. People can cut wood into a shelf, but the wood stays a natural material. Making an object is different from making a new material.

Follow a material into a factory

A manufactured material is made by people. You can also call it “human-made.” Every manufactured material starts with natural materials.

Follow wood into a paper factory. People chop it into tiny bits. They mix the bits with water, press them flat, and dry them. The result is paper, a new material. You can bend and tear it in ways you cannot bend and tear a wooden block.

Glass starts with sand and other ingredients heated in a furnace. Bricks start as clay, shaped and baked in a very hot oven called a kiln. Most plastic starts with oil from deep underground.

Factories also make steel and aluminum. To make steel, people get iron out of rock using great heat. They mix it with a little carbon. Making aluminum from rock needs electricity as well as heat.

Sort by the material's story

Try sorting wood, wool, rock, plastic, glass, and paper.

1. Wood comes from trees, wool from sheep, and rock from the ground. Put these in the natural group.
2. People change starting materials to make plastic, glass, and paper. Put these in the manufactured group.

There are three materials in each group. Paper's story starts with a tree, but people turn the wood into a new material.

A cotton shirt has a different story. Cotton is spun and woven into cloth, but it stays cotton. Its material is natural. A polyester shirt uses a manufactured fiber. Look at a clothing label to find the fiber's name.

Rubber has two possible stories. Natural rubber comes from the milky sap of rubber trees. Factories also make rubber from oil. You need to know its source before sorting it.

A towel feels soft. A window lets you see outside. Softness and being see-through are properties. A property tells you what a material is like or what it does.

Look, touch, and listen

Look at a piece. Is it shiny or dull? What color is it? Can you see through it? Touch it gently. Is it rough or smooth, hard or soft? Listen when you tap it gently. Never taste materials to find out about them.

Some words tell different things. “Smooth” describes the surface you touch. “Shiny” describes how the surface looks in light. A material can be smooth without being shiny.

Scientists use these words too:

Clear window glass is transparent. A wooden block is opaque. A sheet of paper is flexible. A wooden ruler is rigid.

Describe a whole piece

Imagine holding aluminum foil. Look at its surface, then gently bend it. You could say, “It is shiny, smooth, thin, and bendy. I cannot see through it.” Squeeze it and you hear a crinkling sound.

Now describe a sanded wooden block. “It is hard, smooth, stiff, and dull.” Two very different materials can share a property: the foil and block both feel smooth.

Use words that match what you notice. “Sandpaper is rougher than writing paper” compares their surfaces. Pressing a fingernail gently into modeling clay leaves a mark. Pressing it into rock does not. That helps you compare hardness.

Make a helpful comparison

A huge wooden log can weigh more than a little metal key. To compare how heavy materials feel, use pieces of the same size. Then a bigger piece does not get an unfair start.

Touching can also surprise you. Metal and wood kept in the same room can have the same temperature. Yet metal feels cooler. It takes warmth from your fingers faster. A cool feeling does not always mean a lower temperature.

Looking cannot tell you everything. A simple test helps you find out what a material does. Start with a prediction: what you think will happen. Then try it and record what happens.

Try bending and strength tests

Hold a strip and gently try to bend it. A flexible strip bends easily. A rigid piece stays stiff.

A strong material does not tear or break easily. A weak material tears or breaks easily. To compare strength, hang small matching weights from strips. Add one weight at a time. Record how many each strip holds before it tears.

Use the same strip size and the same way of hanging. Change only the material. This is a fair test. If one strip is much wider, its size could help it hold more.

Watch where water goes

Waterproof means water cannot get through. Absorbent means a material soaks up water and holds it. These words describe different things.

Put a piece over a cup. Add one spoonful of water. Watch the top, the piece, and the cup below.

• Water stays on top and none passes through: the piece is waterproof.
• Water soaks into the piece: it is absorbing water.
• Water reaches the cup: the piece lets water through.

A dry cup alone is not enough. A paper towel might hold all the water inside it. You need to check whether the piece soaked it up.

A net bag shows another possibility. Water runs through its holes, but the net does not soak up and hold it. It is neither waterproof nor absorbent.

Keep a record

Here is a test using equal-sized pieces and one spoonful each.

Two of the four pieces were waterproof.

Record what you see, even when it surprises you. “I thought the cloth would keep water out, but it soaked through” is a useful result.

You can put materials into groups by a property they share. This is sorting. First choose your rule. Then check every piece using that rule.

Use one rule

Try “bendy” and “not bendy.” You have a metal spoon, a wooden block, a rubber band, a glass marble, paper, and a sock.

The band, paper, and sock bend easily. Put them in “bendy.” The spoon, block, and marble stay stiff with gentle handling. Put them in “not bendy.” There are three in each group.

Now change the rule to “shiny” and “dull.” The spoon and marble are shiny. The block, band, paper, and sock are dull. You get different groups because you asked a different question.

The sock's color does not decide where it goes in a bendy group. Color is a property too, but bendiness is the rule you chose.

Use two circles

Draw two circles with a shared space in the middle. Label one “hard” and the other “shiny.” Check both properties before placing each object.

1. The metal spoon is hard and shiny. Put it in the shared middle, called the overlap.
2. The wooden block is hard but dull. Put it in the hard circle, outside the middle.
3. The foil is shiny but not hard. Put it in the shiny circle, outside the middle.
4. The sock is neither hard nor shiny. Put it outside both circles.

The middle is a place for things that fit both rules. The space outside is a place for things that fit neither.

Test the piece you have

Groups can contain different materials. Glass and some plastic are both transparent. Metal, glass, plastic, and rubber can all keep water out.

One material can also belong in different groups. A plastic bag is flexible; a plastic toy brick is rigid. A sheet of paper bends easily, but thick cardboard is much stiffer. Try the actual piece before placing it. Its material name alone may not tell you how that piece behaves.

Press a sponge and it gets smaller. Pull a rubber band and it gets longer. A push or pull can change an object's shape.

Name the action

Squashing uses a push. You can bend paper by pushing it into a curve. Stretching uses a pull. When you twist, your hands turn opposite ways, pushing and pulling.

Stretch rubber bands and balloons gently, away from faces.

Follow a changing shape

Start with a ball of modeling clay.

1. Roll it into a long snake.
2. Press it into a flat pancake.
3. Make two snakes and twist them into a rope.

Look at each new shape. You have not added or taken away any clay. It is still the same material, and you have the same amount.

The same is true of foil. Squash a sheet into a ball and it is still aluminum foil. It keeps its shiny surface. Bending a paper clip changes its shape, but it stays metal.

Some pieces change easily under your hands. Clay, foil, and sponge do. A rock or thick wooden block hardly changes when you gently push it.

Use shape to help a material

A flat sheet of paper can sag between two supports. Fold it back and forth into a zigzag. These folds make it stiffer, so a paper bridge can hold more. You changed the shape without changing the material.

People also twist thin cotton or wool strands together. The joined strands make stronger thread or yarn than a single thin strand.

“Hard” does not mean “cannot bend.” A steel paper clip is hard, but its thin shape lets you bend it. A strong push can also dent metal. Glass behaves differently: it can break instead of bending.

What happens after you let go? A sponge puffs back up. Clay keeps a new shape. Dry spaghetti can snap. Watch both the change and what follows it.

Watch the return

An elastic material springs back to its first shape. A rubber band returns after a gentle stretch. A sponge returns after a squash. A metal spring can return too.

Clay and foil behave differently. Stretch clay into a long strip and let go. It stays long. Fold foil and it keeps the fold. Stretching alone does not tell you something is elastic. You must see whether it returns.

A brittle material cracks or snaps instead of bending. Chalk, glass, dry crackers, and dry spaghetti are brittle. The broken pieces keep their material. Crushed chalk is still chalk, even when its pieces are powder.

Measure the extra length

A ruler shows how far a band stretches. Measure before and during the pull. Line one end up with zero each time.

Suppose a band starts at 10 cm. A bag of five marbles pulls it to 16 cm.

1. The first length is 10 cm.
2. The stretched length is 16 cm.
3. Find the extra length: $16-10=6$.

The band stretched 6 cm. It did not stretch 16 cm. That is its whole length while pulled.

Compare two bands fairly

Try a thicker band that also starts at 10 cm. Hang the same bag of five marbles from it. It reaches 13 cm.

Its stretch is $13-10=3$ cm. The thin band stretched 6 cm, and the thick band stretched 3 cm. The thin band stretched 3 cm more.

Use the same pull and equal starting lengths for a fair comparison. Write down the extra length, not just the final length.

The band stretched most in this test. The paper's change was too small to measure. Even an elastic band can snap or stay longer if pulled too far.

A material is suitable when it helps an object do its job well. Start with the job. Then look for the properties that help.

Choose step by step

Think about a window.

1. What must it do? Let you see outside and keep rain out.
2. What properties help? It needs to be transparent, waterproof, and rigid.
3. What material has them? Glass does.
4. Why choose it? “Glass suits a window because it is see-through, waterproof, and stiff.”

Wood is strong and stiff too, but you cannot see through it. It suits a frame, not the pane you look through.

The word because helps connect a choice to a reason. Try, “___ suits ___ because it is ___.” Fill the last space with a property that helps the job.

Check every need

An umbrella must keep rain out and fold up. Its cover needs to be waterproof and bendy. A waterproof fabric cover works well. Thin metal pieces make a strong frame that can fold at its joins.

Paper can fold, but ordinary paper soaks up rain and tears when wet. Glass keeps water out, but it is stiff and breakable. One helpful property is not always enough.

A favorite color can make you like an umbrella. It does not tell you whether the cover keeps rain out. Choose useful properties first.

Match other jobs

A towel needs to take water in. Boots need to keep water out. Those jobs need different water properties.

Brick and some stone can soak up water. Builders use the way walls fit together to keep rain from getting inside. Hardness and strength make the materials useful for supporting the house.

A bridge also needs to hold weight. Strong, stiff wood, metal, or stone can help.

Materials do not have just one job. Wood can make a table, a pencil, or a boat. Plastic can make a bottle, a chair, or a bag. The shape and properties help each object work.

Compare choices for one job

Several materials can do the same job. A spoon can be wood, metal, or plastic. A bag can be paper, plastic, or fabric. Think about what matters for that use.

Many paper cups have a thin plastic lining. It keeps the drink from soaking into the paper. The cup has two materials with different jobs.

There can be several useful choices. How heavy an object is, its cost, and how long it lasts can help people decide.

Give different parts different materials

A bicycle has a strong metal frame. Its rubber tires grip the road. Its seat has a soft part to sit on. The whole bicycle would not work well if every part were soft like the seat.

A pan has another set of needs. Metal lets heat pass through quickly, helping the pan heat food. Wood and plastic let heat pass through more slowly. Many pan handles use them to help protect hands from heat.

This also explains why a metal spoon left in hot soup becomes hot quickly. A wooden spoon in the same soup stays much cooler.

Think about movement

A toy car rolls farther on a smooth wooden floor than on soft carpet. The carpet slows it more.

But sometimes you want more grip. Rubber helps bike tires hold the road. It also helps sneaker soles grip the ground. A surface that helps a wheel roll freely may not be the surface that helps your shoe stop slipping.

A test gives you results, also called data. Use them to choose a material that does the job well. First check what the numbers mean.

Choose a cover

You want a raincoat for a teddy bear. Put equal-sized pieces over cups. Add 10 drops of water to each.

The coat needs to keep water out. Any drops through mean the material is not waterproof. Cotton cloth and paper towel both let water through. Fewer drops through the towel do not make it waterproof: it held some water inside.

Now compare the two pieces with zero drops through. Water stayed on top of the plastic and foil. Both stopped it. The coat must also bend without tearing. Plastic does that well; foil crinkles and tears easily.

You can explain, “I chose plastic because no drops came through, and it bends without tearing.” You used both the test and another property the job needs.

Choose something for a spill

Now the job changes. You need to soak up water. Add spoonfuls until each equal-sized piece cannot hold any more.

More water held is helpful here. The sponge held most, so it was best for soaking up the spill in this test. It held 3 more spoonfuls than the cloth.

The plastic sheet scored zero in both tables. Zero drops through helped the coat. Zero spoonfuls held did not help with the spill. Read the heading before deciding whether a big or small number is useful.

Make results worth comparing

Keep piece size and the testing method the same. For the cover test, each piece gets the same water amount. For the spill test, use the same spoon and stopping rule. Change only the material.

When you explain a choice, name the material and its result. Then say how that result helps the job. “The sponge held 8 spoonfuls, more than the other pieces, so it suited soaking up water.”

You can make a useful object by joining parts. Choose a join that works with the materials and lets the parts do their jobs.

Pick a join

Paper and cardboard join well with glue or tape. Paper clips hold sheets together and come off again. Staples can also join paper. Fabric can be sewn together, and buttons or zippers let clothes open and close. Wood can be joined with wood glue, nails, or screws.

Some joins hold parts still. Others allow movement. Imagine a cardboard puppet whose arm must swing.

1. Overlap the arm and body where they meet.
2. Put a paper fastener, called a brad, through both pieces.
3. The arm can turn around the fastener.

Gluing the whole arm flat against the body would stop it swinging. The join matters as much as the cardboard.

Screws and nuts and bolts can hold parts firmly, then be undone. Buttons, snaps, and hook-and-loop fasteners can open and close many times.

Take apart and build again

Imagine a tower made from 12 blocks. Take it apart, keeping every block. Use them to build a bridge.

You still have 12 blocks. Their materials and shapes have not changed. Only the way you put them together is different. A new object does not always need new pieces.

Use materials again

Reuse means use an object again. A washed yogurt cup can become a seed pot. A shoebox can hold toys. You keep the object, even when you give it a new job.

Recycle means collect used materials to make new things. Old paper can become new paper. Factories can turn old cans into new aluminum cans, and glass bottles into new glass.

These are different actions. When you reuse a jar, you keep using that jar. When you recycle it, its glass becomes material for new objects.

Reduce means use less. Refilling a water bottle helps you use fewer throwaway bottles.

To recycle, first name the material. Paper and cardboard, metal cans, glass jars, and some plastic bottles can be collected in groups. Different towns collect different things. Check your town's rules to find the right bin.