Measure It! Length, Mass, and Capacity

Imagine you are packing a lunchbox. You want to know how long your sandwich is, how heavy your apple is, and how much juice fits in your bottle. These are three different jobs — and each one needs a different measuring tool and a different unit. Can you guess which tool fits which job?

There are three types of measurement you need to know: length, mass, and capacity. **Length** tells you how long or tall something is. We measure length in millimetres (mm), centimetres (cm), metres (m), or kilometres (km). For example, a pencil is about 15 cm long. **Mass** tells you how heavy something is. We measure mass in grams (g) or kilograms (kg). A bag of sugar has a mass of 1 kg. A grape has a mass of about 5 g. **Capacity** tells you how much liquid a container can hold. We measure capacity in millilitres (mL) or litres (L). A large bottle of water holds 1 L. A teaspoon holds about 5 mL. Here is a quick way to remember which unit to use: - Very small lengths → mm or cm - Longer distances → m or km - Light objects → g - Heavy objects → kg - Small amounts of liquid → mL - Large amounts of liquid → L Always write the number first, then the unit right after it — no space between the number and most units (e.g. 25cm or 25 cm are both used, but the unit always follows the number).