Measure length in kilometres and liquid volume in millilitres

What you will learn

• Measure length in kilometres and liquid volume in millilitres

Models used: number sentences, stories, tables.

Before you start

• Choose suitable measurement units

Read the intervals, not the marks

This scale counts in twos. Each space between neighbouring marks is 2 units.

1. Each space between neighbouring marks is 2 units. The pointer is 4 spaces from zero.

   This scale counts in twos. Each space between neighbouring marks is 2 units.

   Length, mass and liquid volume need suitable units. The scale tells us what each interval or displayed amount represents.

2. Each space between neighbouring marks is 2 units. The pointer is 4 spaces from zero.

   The pointer is four spaces from zero. Count 2, 4, 6, 8.

3. Each space between neighbouring marks is 2 units. The pointer is 4 spaces from zero.

   The reading is 8 units. Always look at the scale before counting.

   4 × 2 = 8

Worked example: A new example, together

Convert 3700 ml to litres and ml.

1. The unit changes; the quantity stays the same. Read each value with the heading above its column.

   Read the quantity and unit labels before calculating a difference.

   Changing units changes the number we count, while the measured amount stays the same.

   The unit changes; the quantity stays the same

   Larger unit	Smaller unit
   1 litres	1000 ml
   3 litres	3000 ml

2. The unit changes; the quantity stays the same. Read each value with the heading above its column.

   1 litres = 1000 ml.

   The unit changes; the quantity stays the same

   Larger unit	Smaller unit
   1 litres	1000 ml
   3 litres	3000 ml

   Convert 3700 ml to litres and ml.

   3 litres 700 ml

3. The unit changes; the quantity stays the same. Read each value with the heading above its column.

   1 litres = 1000 ml.

   The unit changes; the quantity stays the same

   Larger unit	Smaller unit
   1 litres	1000 ml
   3 litres	3000 ml

4. The unit changes; the quantity stays the same. Read each value with the heading above its column.

   3 litres = 3000 ml.

   The unit changes; the quantity stays the same

   Larger unit	Smaller unit
   1 litres	1000 ml
   3 litres	3000 ml

5. The unit changes; the quantity stays the same. Read each value with the heading above its column.

   3000 + 700 = 3700 ml; this is 3.7 litres.

   The unit changes; the quantity stays the same

   Larger unit	Smaller unit
   1 litres	1000 ml
   3 litres	3000 ml

6. The unit changes; the quantity stays the same. Read each value with the heading above its column.

   Check the result against the question we started with.

   3700 ÷ 1000 = 3.7 litres.

   We found 3 litres 700 ml. Changing units changes the number we count, while the measured amount stays the same.

   The unit changes; the quantity stays the same

   Larger unit	Smaller unit
   1 litres	1000 ml
   3 litres	3000 ml

Common mistakes to discuss

• Starting at the end of the ruler. Measurement starts at the zero mark, not the edge. Reading from 1 cm makes every length one centimetre too long.

Check your understanding

• Measure length in kilometres and liquid volume in millilitres
• choose and interpret units that match the measured quantity
• check the answer against the original quantities and units

Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.