Glass

I wonder who first discovered glass. This commodity has been a part of civilization from the very beginning. Imagine a world without glass! How dark and dismal it would be. No windows, corrective lenses, telescopes, microscopes, cameras, sparkly drinking containers or mirrors. Life would not be the same without this wonderful discovery. Thank you, whoever found glass!

Glass is not an element, but a combination of several elements. It is a hard, brittle, transparent solid material composed mainly of silica, with additives to change the character of the glass. Common additives are soda, lime, lead, and boron. Each additive changes the properties of the final product. Soda and lime are the most common additives, accounting for about 90% of glass production. Adding lead increases reflectivity, causing the glass to "sparkle." The addition of boron changes the thermal and electrical properties of glass, allowing cookware that can be used in the oven without shattering.

What is the definition of "Brittle" as used in the second paragraph?

Health Care's Numbers Game

The game of health care is a risky one. Today emergency rooms are acting as primary care physicians for thousands of patients. This trend produces a vicious cycle of hospitals raising emergency room costs and passing that increase along to paying patients, who in turn pass it along to insurance companies, who in turn raise rates so even more people cannot afford the premium or the co-payment.

For years, indigent people have used emergency rooms for very minor illnesses rather than seeing an outside doctor, but now emergency rooms are seeing people with insurance, but who cannot afford the co-payment or the deductible for the office visit.

If we don't change the way the healthcare game is played, we're all going to lose.

Which statement from the passage is an opinion, rather than a fact?

The Rainforest

The Amazon River Basin is home to the largest rainforest on Earth. The basin -- roughly the size of the forty-eight contiguous United States -- covers some 40% of the South American continent and portions of eight countries. The basin is drained by the Amazon River, the world's largest river in terms of discharge, and the second-longest river in the world after the Nile.

Since 1970, over 600,000 square kilometres (232,000 square miles) of the Amazon rainforest have been destroyed. This deforestation is mainly due to land clearing for pastureland by commercial and speculative interests, misguided government policies, and commercial exploitation of forest resources.

Deforestation of the rainforest has long-term implications. The loss of habitat for many creatures ensures their extinction. The loss of vegetation depletes the oxygen in the atmosphere, which some say causes global warming.

What is the definition of "habitat" as used in the last paragraph?

All That Jazz

Jazz is an American musical art form which originated at the beginning of the 20th century in African-American communities in the Southern United States. It derived from a confluence of African and European music traditions. From its early development until the present, jazz has also incorporated music from 19th and 20th century American popular music. The word jazz began as a West Coast slang term of uncertain derivation and was first used to refer to music in Chicago in about 1915. Improvisation is one of the key elements of jazz and a fundamental part of the nature of the music. In jazz, the skilled performer will interpret a tune in very individual ways, never playing the same composition exactly the same way twice. Depending upon the performer's mood and

personal experience, interactions with fellow musicians, or even members of the audience, a jazz musician/performer may alter melodies, harmonies or time signature at will.

How does the author regard jazz?