Year 8 Science · Unit 2 · Lesson 21
Foundation Worksheet
Learning Goals
Fill the gap
Choose the correct word from the word bank. Each word is used once at most. Two words will not be used.
Aluminium is the most metal in Earth’s crust, but before 1886 it was costly because nobody could it from its ore cheaply. The Hall-Héroult uses electricity to do this, and it made aluminium cheap. Asbestos was used in homes because it does not and it resists heat. Over many years, showed that breathing its fibres causes disease, and Australia it in 2003.
1. Name the cancer that asbestos fibres can cause, and give one reason it took so long for people to notice the harm.
Put the aluminium story in order
Number the events from 1 (first) to 6 (last).
| Order (1–6) | Event |
|---|---|
| Aluminium is so cheap it is made into foil that is thrown away after one use. | |
| Aluminium is known, but it is so hard to extract that it is a luxury metal. | |
| Factories scale up; aluminium is now cheap enough for cookware and aircraft. | |
| The Hall-Héroult electrolysis process is discovered. | |
| Today, one smelter (Tomago, NSW) makes hundreds of thousands of tonnes a year. | |
| The cheaper aluminium is tried out in small-scale uses to show it works. |
Read the data
| When | What happened |
|---|---|
| 1920s | Asbestosis, a scarring of the lungs, is described in asbestos workers. |
| 1950s | A link between asbestos and lung cancer is established. |
| 1960 | Mesothelioma, a cancer of the lining of the lungs, is tied to asbestos. |
| 2003 | Australia bans asbestos outright. |
Source: dates from the lesson. Mesothelioma often appears 20 to 40 years after a person breathes in the fibres.
2. (a) How many years passed between the mesothelioma link and the Australian ban? (b) A builder breathed in asbestos fibres in 1975. Between which two years might mesothelioma appear?
(a) years
(b) From to
Scenario: Grandad’s fibro shed
Grandad’s garden shed was built in the 1960s from asbestos cement sheets. He says: “Asbestos was a great material back then. Nothing about it has changed, so it’s still a great material now.”
3. Grandad is right that asbestos itself has not changed. Explain why its use has still changed. Compare it with the aluminium story.
Fill the gap
abundant; extract; process; burn; evidence; banned. Not used (2): rare, melt.
1. Mesothelioma. It often appears 20 to 40 years after the fibres are breathed in, so the harm showed up long after the exposure. [2 marks: 1 disease, 1 reason]
Put the aluminium story in order
Reading down the table as printed: 5, 1, 4, 2, 6, 3.
Luxury metal, then the Hall-Héroult process (1886), then small-scale uses, then factories scale up, then throw-away foil, then today’s large smelters.
Read the data
2. (a) 2003 − 1960 = 43 years. (b) 1975 + 20 = 1995 and 1975 + 40 = 2015, so between 1995 and 2015. [2 marks: 1 each]
Show What You Know
3. Marking guide (points expected): 2 two useful properties (1 each), for example it does not burn, resists heat and chemicals, does not rot, is strong for its weight, was cheap; 1 the properties have not changed; what changed is scientific understanding; 1 evidence showed that breathing the fibres causes asbestosis, lung cancer and mesothelioma; 1 the evidence built up from the 1920s to 1960 but the ban came only in 2003, partly because the disease appears 20 to 40 years after exposure, so the harm was easy to argue about; 1 contrast: with aluminium, a discovery (the Hall-Héroult process) made a substance available; with asbestos, new evidence took a substance away, so discoveries can change uses in both directions. [6 marks]
Common error to watch for: saying asbestos “became dangerous” or “changed”. It was always harmful to breathe; only our evidence and understanding changed. (Safety note for class discussion: old asbestos sheeting should not be cut, drilled or broken; it needs professional advice.)