STEM - Free Printable

Let's solve this step-by-step based on the worksheet titled "Materials and Their Properties".

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Part 1: Complete the Table

We need to evaluate each item for the following properties:

- Hard
- Soft
- Transparent
- Bendy
- Rigid
- Stretchy
- Waterproof

We'll go through each item one by one, considering typical materials used to make them (e.g., a mug is usually ceramic, a towel is cotton, etc.).

| Item | Hard | Soft | Transparent | Bendy | Rigid | Stretchy | Waterproof |
|------------|------|------|-------------|-------|-------|----------|------------|
| Mug | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Chair | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Towel | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✔ |
| Pencil | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Door | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Ruler | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Gloves | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✔ |
| Salt Pot | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Shoe lace | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✔ |

#### 🔍 Explanation of Each:

- Mug: Usually made of ceramic or glass → hard, rigid, waterproof, not transparent.
- Chair: Wood or plastic → hard, rigid, waterproof, not soft/stretchy.
- Towel: Cotton or fabric → soft, bendy, stretchy, absorbent but waterproof? – Wait!
- Important: Towels are *not* waterproof — they absorb water. So:
- Waterproof: ✘
- Corrected: Towel → Not waterproof
- Pencil: Wood + graphite → hard, rigid, not stretchy, not transparent.
- Door: Wood or metal → hard, rigid, not soft/bendy/stretchy, opaque, waterproof.
- Ruler: Plastic or wood → hard, rigid, not stretchy.
- Gloves: Fabric or leather → soft, bendy, stretchy, not transparent.
- Salt Pot: Ceramic or glass → hard, rigid, waterproof (if sealed), not soft.
- Shoe lace: Fabric or synthetic thread → soft, bendy, stretchy, not waterproof.

✔ But towels and shoe laces are not waterproof — they absorb water.

So, correct Waterproof column:

| Item | Waterproof |
|------------|------------|
| Mug | ✔ |
| Chair | ✔ |
| Towel | ✘ |
| Pencil | ✔ |
| Door | ✔ |
| Ruler | ✔ |
| Gloves | ✔ (if rubberized) or ✘ (if fabric) → likely ✘ unless specified |
| Salt Pot | ✔ |
| Shoe lace | ✘ |

But gloves can be made of waterproof materials (like rubber), but common fabric gloves aren't. Let’s assume standard classroom items.

So revised table:

| Item | Hard | Soft | Transparent | Bendy | Rigid | Stretchy | Waterproof |
|------------|------|------|-------------|-------|-------|----------|------------|
| Mug | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Chair | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Towel | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✘ |
| Pencil | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Door | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Ruler | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Gloves | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✘ |
| Salt Pot | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Shoe lace | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✘ |

> ✔ Note: For gloves and shoe laces, if made of synthetic material, they might be somewhat waterproof, but generally, in basic science, we consider them not waterproof unless stated.

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Part 2: Explain Why Materials Are Selected

Use these words:
rigid, flexible, impermeable, durable, smooth, warm, insulator, grip, soft, hard, transparent, opaque, light, tough

Let’s go through each:

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#### 1. Glass for windows
- Transparent → allows light to pass through.
- Hard → resists damage.
- Rigid → holds shape.
- Impermeable → stops air/water from passing.
- Smooth → easy to clean.
- Opaque? No → it’s transparent.
- Why? Needs to let light in, be strong, and not let rain in.

✔ Answer: Glass is chosen because it is transparent, allowing light into rooms; rigid and hard to withstand impact; and impermeable to keep out rain and wind.

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#### 2. Rubber for soles
- Flexible → bends with foot movement.
- Tough → resists wear and tear.
- Grip → provides traction.
- Impermeable → keeps feet dry.
- Durable → lasts long.
- Soft → comfortable.

✔ Answer: Rubber is chosen because it is flexible and durable, providing comfort and long life; it has good grip to prevent slipping; and it is impermeable to keep feet dry.

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#### 3. Wool for a jumper
- Warm → traps body heat.
- Soft → comfortable against skin.
- Insulator → reduces heat loss.
- Flexible → moves with body.
- Tough → resistant to tearing.

✔ Answer: Wool is chosen because it is a good insulator and keeps the body warm; it is soft and flexible, making it comfortable to wear.

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#### 4. Plastic for a socket
- Insulator → does not conduct electricity.
- Rigid → holds shape.
- Impermeable → protects from moisture.
- Durable → lasts long.
- Smooth → safe to touch.
- Opaque → hides internal wiring.

✔ Answer: Plastic is chosen because it is an insulator, preventing electric shocks; it is rigid and durable to protect wires; and impermeable to moisture.

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#### 5. Leather for boxing gloves
- Tough → resists damage.
- Flexible → conforms to hand.
- Durable → lasts many uses.
- Soft → cushions impact.
- Grip → holds hands securely.
- Impermeable → keeps hands dry.

✔ Answer: Leather is chosen because it is tough and durable, protecting the hands during impact; it is flexible and soft for comfort; and it provides grip and is impermeable to sweat.

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#### 6. Cotton for a towel
- Soft → gentle on skin.
- Absorbent → not waterproof!
- Flexible → can be folded.
- Tough → withstands washing.
- Light → easy to carry.

But note: Cotton is NOT waterproof — it absorbs water.

✔ Answer: Cotton is chosen because it is soft, absorbent, and flexible, making it ideal for drying; it is also durable and light.

> ⚠️ Important: The property "waterproof" is not true for cotton, but its absorbency is key here.

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#### 7. Rubber for a hot water bottle
- Impermeable → doesn’t leak.
- Flexible → can expand when filled.
- Insulator → slows down heat loss.
- Tough → resists punctures.
- Soft → comfortable to hold.

✔ Answer: Rubber is chosen because it is impermeable (won’t leak), flexible (can hold liquid), and a good insulator (keeps heat in); it is also soft and tough.

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#### 8. Wood for a chair
- Hard → supports weight.
- Rigid → maintains shape.
- Durable → lasts long.
- Tough → resists breaking.
- Smooth → comfortable to sit on.
- Light → easier to move than metal.

✔ Answer: Wood is chosen because it is hard, rigid, and durable, supporting body weight; it is also tough and smooth, making it comfortable and long-lasting.

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✔ Final Summary

#### Part 1 Table (Corrected)

| Item | Hard | Soft | Transparent | Bendy | Rigid | Stretchy | Waterproof |
|------------|------|------|-------------|-------|-------|----------|------------|
| Mug | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Chair | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Towel | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✘ |
| Pencil | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Door | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Ruler | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Gloves | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✘ |
| Salt Pot | ✔ | ✘ | ✘ | ✘ | ✔ | ✘ | ✔ |
| Shoe lace | ✘ | ✔ | ✘ | ✔ | ✘ | ✔ | ✘ |

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#### Part 2 Answers

1. Glass for windows: Transparent, rigid, hard, impermeable → lets light in and keeps out weather.
2. Rubber for soles: Flexible, tough, provides grip, impermeable → comfortable and safe.
3. Wool for a jumper: Warm, soft, insulator → keeps body warm.
4. Plastic for a socket: Insulator, rigid, impermeable → prevents electric shock and protects.
5. Leather for boxing gloves: Tough, flexible, soft, grip → protects hands and absorbs impact.
6. Cotton for a towel: Soft, absorbent, flexible, durable → dries well and is comfortable.
7. Rubber for a hot water bottle: Impermeable, flexible, insulator, soft → holds liquid and retains heat.
8. Wood for a chair: Hard, rigid, durable, tough → supports weight and lasts.

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✔ This completes the worksheet with scientific reasoning and accurate material properties.