# The History of Glass: answers and explanations

Cambridge IELTS 12, Test 4, Reading Passage 1

Source: Passage, questions and answer key from Cambridge IELTS 12, Test 4, Reading Passage 1. © Cambridge University Press & Assessment. Used for educational practice. Explanations and evidence notes are written by Testmigo.

## Answer key

| Q | Answer | Proof |
| --- | --- | --- |
| 1 | obsidian | a type of natural glass - obsidian - formed in places such as the mouth of a volcano |
| 2 | spears | was first used as tips for spears. |
| 3 | beads | this took the form of glazes used for coating stone beads. |
| 4 | impurities | The glass made during this time was highly coloured due to the impurities of the raw material. |
| 5 | Romans | The secret of glass making was taken across Europe by the Romans during this century. ... it was not until their empire collapsed in 476 AD |
| 6 | lead | by introducing lead to the raw materials used in the process |
| 7 | clouding | He attempted to counter the effect of clouding that sometimes occurred in blown glass |
| 8 | taxes | only really started to develop after the repeal of the Excise Act in 1845 ... heavy taxes had been placed on the amount of glass melted in a glasshouse |
| 9 | TRUE | more than three times quicker than any previous production method |
| 10 | FALSE | the first fully automated machine was developed in the USA by Michael Owens - founder of the Owens Bottle Machine Company |
| 11 | NOT GIVEN | It has become a modern, hi-tech industry operating in a fiercely competitive global market |
| 12 | TRUE | with growing consumer concern for green issues, glass bottles and jars are becoming ever more popular |
| 13 | FALSE | As less energy is needed to melt recycled glass than to melt down raw materials, this also saves fuel and production costs. |

## Why these answers are right

**1. obsidian.** The notes ask what material early humans used for sharp points. Paragraph A names a type of natural glass, obsidian, formed when volcanic heat melted sand, and says it was first used as tips for spears, so obsidian is the answer.

**2. spears.** This gap is the object whose sharp points were made from obsidian. Paragraph A says the natural glass was first used as tips for spears, and 'tips' matches 'sharp points', so spears is the word to copy from the passage.

**3. beads.** The note says stone things were coated with man-made glass in 4000 BC. Paragraph A explains that this early glass took the form of glazes used for coating stone beads, so beads is the missing noun, while glazes is the coating itself.

The why and the trap for questions 4 onwards are free with an account on the [answers page](https://testmigo.com/ielts/reading/the-history-of-glass/answers).

[Practice The History of Glass](https://testmigo.com/ielts/reading/the-history-of-glass)