Choosing measurement units
Choose and use appropriate standard units to measure length (m/cm), mass (kg/g), and capacity (litres/ml) to the nearest appropriate unit
What a learner can do afterwards
- Measure the length of a table in centimetres using a ruler
- Weigh an object in grams using a scale
- Measure the capacity of a container in millilitres using a measuring jug
1 · Read
Length uses centimetres (cm) or metres (m). Centimetres are convenient for short objects. Use a ruler: line up one end with zero and read the other end. Do not start at the ruler's physical edge unless zero is there. One metre is 100 centimetres.
Mass uses grams (g) or kilograms (kg). Grams are convenient for a light object such as a grape. Use a scale, set the empty scale to zero, and check its unit. A reading of 450 on a scale set to g means 450 g. One kilogram is 1000 grams.
Liquid volume uses millilitres (ml) or litres. Millilitres are convenient for small amounts. Use a measuring jug and read its marks at eye level. Record the number and the marked unit. One litre is 1000 ml. Litres and millilitres are volume units, not mass units.
Metres are convenient for long lengths and tall buildings. Centimetres could describe the same length, but would give a larger number. Each metre is 100 cm. For example, 3 m is 300 cm. To change whole metres to centimetres, use 100 cm for each metre.
Kilograms are convenient for heavier masses. A scale set to kg with a reading of 2 gives a mass of 2 kg. Read the selected unit rather than guessing it from the object. To write kilograms in grams, count 1000 g for each kilogram: 1000 g, then 2000 g for 2 kg.
Capacity means how much a container can hold, not how much is inside now. To measure capacity with a jug, fill the container completely and measure all the liquid needed. Record the jug's unit. Litres are convenient for a large container; millilitres for a small one.
Choose a unit for the attribute and amount. Use the matching tool, read its unit, and record the number with that unit.
Readings, questions and flashcards written for this topic. The referenced video is by Khan Academy.
2 · Watch
Take it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
18 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.