Plastics are a synthetic material that can be cast into virtually any shape. Plastics can range from hard to soft, can be flexible or firm, transparent or opaque. Plastics of various kinds are used in the making or packaging of virtually everything nowadays.
Porcelain is a hard, white ceramic that is commonly used to make plates and cups, some dolls, and bathroom ware like baths and toilets. When porcelain is very thin, it is slightly translucent.
A rod is a relatively long, thin, straight object, very similar to a stick. Rods can be made from metal, plastic or wood. They can be used for a wide variety of things, such as fishing rods, magic wands, staffs and curtain rods.
The rods in the picture are steel reinforcing rods.
A rope is a very thick, strong piece of string. You use rope for tying big things, like the sails on a yacht, like the rope in the picture. A fun use for rope is a tug 'o war. Rope is usually made from the fibre from coconut shells, or a modern fibre like nylon, twisted together so it is thicker.
If you need to tie something that is too big or heavy for ordinary rope, you either need rope made from strands of metal or use some steel chain.
Sand is something that beaches are made of. Beach sand is made up of ground up rocks and fragments of shells. Beach sand can have quite large bits in it compared to garden dirt. Desert sand is just made from ground up rocks.
The colour of sand varies depending on what kind of rocks or shells went into making it.
Sawdust is the name for the fine particles of wood that are made when you cut wood up with a saw. In the picture you can see the sawdust being made by the man using the chainsaw.
Sawdust makes really good bedding for pet mice and guinea pigs.
Scraps are small pieces of something, usually the remnants from cutting out what you want from something. Scraps can often be reused for other projects.
Scrap might also describe general waste that may or may not be able to be recycled, such as scrap metal.