WorksheetsAbout this worksheet
Changing one unit into another: 4 km into metres, 3,000 g into kilograms, 2 h 15 min into minutes. The facts to know are few: 1 km = 1,000 m, 1 m = 100 cm, 1 cm = 10 mm, 1 kg = 1,000 g, 1 L = 1,000 mL, 1 hour = 60 minutes, 1 minute = 60 seconds.
What this skill is
The same length, weight or amount can be written in a big unit or a small one. Converting means changing the unit without changing the amount. Metric units for length, weight and capacity are built on tens, hundreds and thousands, so converting them is multiplying or dividing by 10, 100 or 1,000. Time is different and works in sixties.
A worked example
- 3 km 250 m in metres. 1 km is 1,000 m, so 3 km is 3,000 m. Add the 250 m: 3,250 m.
- 4,500 mL in litres. 1,000 mL make 1 L. 4,500 ÷ 1,000 = 4.5, so it is 4.5 L, or 4 L 500 mL.
- 2 h 35 min in minutes. 2 hours is 2 × 60 = 120 minutes. Add 35: 155 minutes.
A sense check for every answer: a smaller unit needs a bigger number, and a bigger unit needs a smaller number.
Tips for parents and teachers
- Bigger unit to smaller unit: multiply. Smaller unit to bigger unit: divide.
- Time is the odd one out. It works in sixties, not in tens.
- Keep a small table of the facts on top of the sheet for the first few days.
How to use this sheet at home and in class
- At home: read the labels in the kitchen. A 500 g packet, a 1 L bottle and a 250 mL glass give real questions: how many glasses in the bottle?
- In class: take one measure at a time (length, then weight, then capacity, then time) and keep "All mixed" for the end of the unit.
- Let children keep a fact table on the desk at first. The aim in the early days is choosing between multiply and divide, not memory.
Mistakes to watch for
- Multiplying when dividing was needed, so 3,000 g becomes 30,00,000 kg. The sense check catches it.
- Treating time like a decimal: writing 2 h 35 min as 2.35 hours or as 235 minutes.
- Using 100 where 1,000 is needed. There are 100 cm in a metre but 1,000 m in a kilometre, 1,000 g in a kilogram and 1,000 mL in a litre.
What to try next
- Decimals worksheets: answers such as 4.5 L.
- Telling time worksheets: if hours and minutes are unsure.
- Area and perimeter worksheets: units in use.