Learning Objectives
- Understand and use units of length, weight, and capacity
- Convert between different units of measurement
- Estimate and measure using appropriate units
- Solve word problems involving measurement
Key Concepts
Units of Length
Length tells us how long something is. We use millimetre (mm), centimetre (cm), metre (m), and kilometre (km). 1 cm = 10 mm. 1 m = 100 cm. 1 km = 1000 m. Use mm for very tiny things (like the thickness of a coin), cm for small things (like a pencil), m for bigger things (like a room), and km for distances (like between cities).
Units of Weight
Weight tells us how heavy something is. We use milligram (mg), gram (g), and kilogram (kg). 1 g = 1000 mg. 1 kg = 1000 g. A small tablet weighs about 500 mg. A biscuit weighs about 10 g. A bag of rice weighs about 5 kg. Your body weight is measured in kg. Choose the right unit depending on what you are measuring.
Units of Capacity
Capacity tells us how much liquid something can hold. We use millilitre (mL) and litre (L). 1 L = 1000 mL. A teaspoon holds about 5 mL. A glass holds about 250 mL. A water bottle holds about 1 L. A bucket holds about 15 L. Use mL for small quantities and L for large quantities.
Converting Between Units
To convert from a bigger unit to a smaller unit, multiply. For example: 3 kg = 3 x 1000 = 3000 g. To convert from a smaller unit to a bigger unit, divide. For example: 2500 mL = 2500 ÷ 1000 = 2.5 L. Always convert to the same unit before adding, subtracting, or comparing measurements.
Important Terms
- Length: How long something is (mm, cm, m, km)
- Weight: How heavy something is (mg, g, kg)
- Capacity: How much liquid something can hold (mL, L)
- Conversion: Changing from one unit to another
- Estimate: Making a smart guess before measuring
Quick Revision
- 1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm
- 1 kg = 1000 g, 1 g = 1000 mg
- 1 L = 1000 mL
- Bigger to smaller unit: multiply
- Smaller to bigger unit: divide
- Convert to same unit before comparing or calculating