I need help with my science homework, i dont quite understand this?

There are drinking gles, gl bowls, gl bottles (wine bottles), lightbulbs, mirrors, cathode ray tubes, and gl windows. "Drinking gles, bowls, and bottles are often made of gl, as are light bulbs, mirrors, cathode ray tubes, and windows. In laboratories doing research in chemistry, biology, physics and many other fields, flasks, test tubes, lenses and other laboratory equipment are often made of glass. For these applications, borosilicate glass (such as Pyrex) is usually used for its strength and low coefficient of thermal expansion, which gives greater resistance to thermal shock and allows for greater accuracy in laboratory measurements when heating and cooling experiments. For the most demanding applications, quartz glass is used, although it is very difficult to work. Most such glass is mass-produced using various industrial processes, but most large laboratories need so much custom glassware that they keep a glassblower on staff. Volcanic glasses, such as obsidian, have long been used to make stone tools, and flint knapping techniques can easily be adapted to mass-produced glass." (wikipedia) Glass is also used to make JEWELRY. Some criminals feign glass as diamonds but it is easily detectable. since glass can shatter easily.