All children need to know the following facts and be confident when converting from one to another.
1000 grams = 1kg 1000 millilitres = 1L
250g = 0.25kg = ¼ kg 250ml = 0.25 L= ¼ L
500g = 0.5 kg = ½ kg 500ml = 0.5 L – ½ L
750g = 0.75kg = ¾ kg 750ml = 0.75ml = ¾ L
1000 metres = 1km 60 minutes = 1 hour
500m = 0.5 km = ½ km 15 minutes = ¼ hour
100cm = 1m 30 minutes = ½ hour
50cm = 0.5 m = ½ m 60 seconds = 1 minute
10 mm = 1cm
5mm = 0.5 cm = ½ cm
Children also need to be able to read the scale on the measuring jug / scales or ruler and be able to recognise the equivalent analogue and digital time.
Activities to support this knowledge:
(It is fine to measure approximately for ease of conversion, e.g the potato can weigh 30g rather than 31.4g)
- Weight: Using scales weigh a potato and establish how much it weighs in g and kg. How many potatoes to make a kg? etc. Repeat for other items.
- Capacity: Fill a 1litre jug or bottle with water. Find containers that are smaller than 1 litre e.g. a cup. How many times can you fill the smaller container from the 1 litre jug? How many ml in the smaller container? If we filled 2 small containers how many ml? etc. Repeat for larger containers. How many ml will it take to fill the kettle? / The washing up bowl? Etc.
- Length: Use a ruler / tape measure to measure different items. Convert from mm to cm or m. Choose large items such as the bed as well as tiny objects. Can children find the difference in length between two objects?
- EXT: If children can measure the length and width of an item can they use a calculator (or phone) to work out the area (length x width). Or include the height to work out the volume (length x width x height).
- Some children might like the challenge to find the approximate area or volume of a room or of their whole house!
- Time: Play the game Clock Patience - the explanation can be seen at: https://www.wikihow.com/Play-Clock-Patience
- Leave the cards on the table in a clock formation. Make two paper hands. Take turns at placing the hands in the clock and saying the time.
- EXT: What would the time be 15 minutes earlier or later?
- Display a time and convert it to a digital time. Or say a digital time and convert this to the analogue time.
- Turn this into a problem, e.g. ‘The pie goes in the oven at ¼ to 3. It cooks for 40 minutes. What time does the pie come out of the oven?’, or ‘We go for a walk at 2:40 we return home at 3:15 How long were we out for?’, etc.