Which unit would you use?
From the distance between two cities to a spoon of cough syrup, decide what each of twelve everyday things measures, length, mass, volume or time, and choose a unit that suits its size.
Core concept
Every measurement has a quantity (length, mass, volume or time) and a unit; we choose a unit that suits the size, so the number is neither huge nor tiny: kilometres for roads, millimetres for an ant
Topic: Maths in everyday life
When we measure something we need two things: the quantity we are measuring and a unit. Length (how long or far) is in millimetres, centimetres, metres or kilometres. Mass (how heavy) is in milligrams, grams, kilograms or tonnes. volume: How much space something takes up, measured in millilitres or cubic centimetres. All key words (how much space a liquid fills) is in millilitres or litres. Time is in seconds, minutes, hours, days, months or years. We pick the unit that suits the size: nobody says the road from Kathmandu to Pokhara is 200 000 000 mm, or that an ant is 0.000005 km long. The metric units go up in steps of 10, 100 or 1000, which makes them easy to change.
What you will learn
- Tell whether a measurement is a length, a mass, a volume or a time.
- Choose a sensible unit for an everyday quantity.
- Relate metric units: 1 km = 1000 m, 1 kg = 1000 g, 1 L = 1000 mL.
Before you start
- Know the names of the common units.
Materials
- A ruler, a kitchen scale, a measuring jug and a clock
Equipment
- None
Procedure
- Pick an item and find what it measures and a good unit.
- Do this for at least eight items.
- Sort every item into length, mass, volume or time.