Materials

A gel is a type of solid that has some liquid properties too. Gels keep their shape like solids, but with enough time will flow like a liquid. A lot of common items are gels, like hair gel, toothpaste, jello, soft contact lenses and breast implants.

Graphite is a form of carbon. It has the interesting property of being made up of very thin layers that can be easily rubbed off, so is perfect for drawing with. Graphite is the main ingredient of the "lead" in lead pencils.

Graphite can also conduct electricity, so it has many applications in engineering and electronics.

Gravel is small stones, usually used for a decorative landscaping mulch or as an aggregate in building materials like concrete.

Grout is a substance made of water, cement and sand that is used to fill up gaps between hard construction materials like tiles. Grout often contains coloring agents, and can be bought in a huge range of colors.

Hay is dried grass or other crops that has been stored to be fed to animals. Hay usually has the seed heads of the grass in it as well as just the stems and leaves. Hay is different to straw.

Ice is what happens to water when it is so cold that it freezes. You can see ice as snow in winter. Snow is just tiny bits of ice. In summer, people make their drinks cooler by putting ice in them.

Insulation is something that you put in the sides of a container to keep the temperature inside as steady as possible. Fridges have insulated walls to keep the inside cool, and most houses have at least the ceiling insulated to keep the inside cooler in summer and warmer in winter.

Ivory is essentially teeth. Ivory usually refers to elephant's tusks, but any tooth large enough to be carved can be used as ivory. Before plastic was invented, ivory was commonly used for making ornaments, buttons, handles of knives and forks and the most familiar use - piano keys.

Today the trade in ivory is banned in most countries, and plastic or ivory substitutes are used where ivory was once used.

Latex is the milky sap of many different plants. One tree in particular, the Para rubber tree, is used for commercially producing rubber.

Rubber is used in a huge variety of ways. It is used to make rubber bands, erasers, elastic that you find in the waistband of clothes, drive belts inside a car engine, gumboots and the biggest use is tyres.

Leather is a substance made from tanned animal skins, usually cow skins. The tanning process makes skin stronger, harder and means it will last a lot longer.

Leather is used to make shoes, belts, bags, saddles and other horse related gear, some furniture and many other things.