Year 7 Science · Unit 4 · Lesson 4
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Learning Goals
Choose the right instrument
For each job, write which instrument you would use and the unit you would record. Choose from ruler, measuring cylinder, balance, thermometer or stopwatch.
| Measuring job | Instrument | Unit |
|---|---|---|
| How tall a bean plant has grown | ||
| How much water is in a beaker | ||
| How long a trolley takes to roll down a ramp | ||
| How hot a cup of tea is | ||
| The mass of a handful of marbles |
Real-world context
The Bureau of Meteorology, Australia's weather agency, records the weather at thousands of stations across the country. At each station, a thermometer measures air temperature in degrees Celsius, a rain gauge measures rainfall in millimetres, and an anemometer measures wind speed in kilometres per hour. Each instrument is chosen so its range covers the values expected at that place, and so it is sensitive enough to detect the small changes that matter, like a light drizzle or a half-degree drop in temperature overnight.
(a) Match each weather measurement to its instrument and unit. Fill in the table.
| Weather measurement | Instrument | Unit |
|---|---|---|
| Air temperature | ||
| Rainfall | ||
| Wind speed |
(b) A student reads a measuring cylinder by looking down at it from above, instead of at eye level. Explain what error this causes and how the student should read it correctly.
(c) A rain gauge marked in 1 mm steps and a bucket marked only in 50 mm steps could both catch rain. Which is more sensitive, and why does that matter for measuring a light drizzle? Give two reasons.
1. Two thermometers are for sale. One has a range of 10 °C to 50 °C. The other has a range of -30 °C to 120 °C. You need to measure the temperature inside a freezer at -18 °C. Which thermometer must you choose, and why?
2. A digital balance always reads 5 g higher than the true mass. Is the balance sensitive, accurate, both or neither? Explain your answer.
Wrap Up
In one sentence, what was the main idea of this lesson?