A thing can be wood, metal or glass. You can see through glass, and it breaks easily.
Wood, metal and glass
Try it: Woman: Why is your living room so bright? Man: The front door is ___, so a lot of light comes in. Choose what the man says. (wood / glass / metal) Answer: glass — Light comes in through the door, so it is glass.
Word
Pronunciation
Example
wood
Our kitchen table is wood.
metal
This old box is metal.
glass
This bottle is glass.
Plastic and cotton
Plastic is light, and it does not break easily. Cotton is soft, and a lot of clothes are cotton.
Try it: Man: Oh no, I dropped the big salad bowl! Woman: Don't worry. It's ___. Look, it's fine. Choose what the woman says. (glass / cotton / plastic) Answer: plastic — The bowl did not break, so it is plastic.