Year 2: Measuring with a ruler

Method. Line up the start with the 0 mark or count from the start. Read the number at the other end.

1. Line up the 0 with the start. Put the 0 mark at the end of the thing.
   start at 0
2. Read the number at the other end. The other end is at 4 cm.
   end at 4 cm
3. Write the answer.
   4

Check. Count along the ruler from the start to the end: 4 centimetres. ✓

Watch out. Start at 0 is easiest. If the start is not 0, take the start away from the end.

Method. Line up the start with the 0 mark or count from the start. Read the number at the other end.

1. Line up the 0 with the start. Put the 0 mark at the end of the thing.
   start at 0
2. Read the number at the other end. The other end is at 11 cm.
   end at 11 cm
3. Write the answer.
   11

Check. Count along the ruler from the start to the end: 11 centimetres. ✓

Watch out. Start at 0 is easiest. If the start is not 0, take the start away from the end.

Method. Line up the start with the 0 mark or count from the start. Read the number at the other end.

1. Line up the 0 with the start. Put the 0 mark at the end of the thing.
   start at 0
2. Read the number at the other end. The other end is at 10 cm.
   end at 10 cm
3. Write the answer.
   10

Check. Count along the ruler from the start to the end: 10 centimetres. ✓

Watch out. Start at 0 is easiest. If the start is not 0, take the start away from the end.

Method. Line up the start with the 0 mark or count from the start. Read the number at the other end.

1. Line up the 0 with the start. Put the 0 mark at the end of the thing.
   start at 0
2. Read the number at the other end. The other end is at 14 cm.
   end at 14 cm
3. Write the answer.
   14

Check. Count along the ruler from the start to the end: 14 centimetres. ✓

Watch out. Start at 0 is easiest. If the start is not 0, take the start away from the end.

Method. Line up the start with the 0 mark or count from the start. Read the number at the other end.

1. Find the start. The line starts at 3 cm.
   start at 3 cm
2. Find the end. The line ends at 8 cm.
   end at 8 cm
3. Count the length. Take the start away from the end.
   8 − 3 = 5
4. Write the answer.
   5

Check. Count along the ruler from the start to the end: 5 centimetres. ✓

Watch out. Start at 0 is easiest. If the start is not 0, take the start away from the end.

Method. Change to the same unit, then pick the biggest amount.

1. Look at A. A is 6 cm.
   A: 6 cm
2. Look at B. B is 9 cm.
   B: 9 cm
3. Pick the one with the biggest amount. Once the units match, the numbers can be compared.
   B wins
4. Write the answer.
   B

Check. Compare the other amounts too. ✓

Watch out. Read the units first. 2 m is longer than 150 cm, because 2 m = 200 cm.

Method. Find the difference by taking the smaller amount away from the bigger one.

1. Find the bigger amount. The bigger stick is 9 cm.
   9 cm
2. Find the smaller amount. The smaller stick is 4 cm.
   4 cm
3. Take the smaller amount away. Subtract to find the difference.
   9 − 4 = 5
4. Write the answer.
   5

Check. Add the difference back: 4 + 5 = 9. ✓

Watch out. Start with the bigger number, then take the smaller one away.

Method. Change to one unit, then put the smallest amount first.

1. Look at B. B is 4 cm.
   B: 4 cm
2. Look at C. C is 7 cm.
   C: 7 cm
3. Look at A. A is 9 cm.
   A: 9 cm
4. Put the amounts in order. Smallest first
   B, C, A
5. Write the letters.
   B, C, A

Check. Check each pair: the first is never bigger than the next. ✓

Watch out. Compare the numbers after you change to the same unit.

Method. Measure the stick from 0 and read the end. Then compare with what Ruby said.

1. Line up the 0. The stick starts at 0.
   start at 0
2. Read the end. The stick ends at 5 cm.
   end at 5 cm
3. Compare with Ruby. Ruby said 6 cm, but the ruler shows 5 cm.
   5 ≠ 6
4. Write the answer.
   No

Check. The ruler shows 5 cm, so Ruby is not right. ✓

Watch out. Read the end of the stick exactly on the number.

Method. Find the difference by taking the smaller amount away from the bigger one.

1. Find the bigger amount. The bigger line is 14 cm.
   14 cm
2. Find the smaller amount. The smaller line is 6 cm.
   6 cm
3. Take the smaller amount away. Subtract to find the difference.
   14 − 6 = 8
4. Write the answer.
   8

Check. Add the difference back: 6 + 8 = 14. ✓

Watch out. Start with the bigger number, then take the smaller one away.

Method. Look at the stick from 1 to 7. Take 1 away from 7.

1. Find the start. The stick starts at 1 cm, not at 0.
   start at 1 cm
2. Find the end. The stick ends at 7 cm.
   end at 7 cm
3. Count the length. Take the start away from the end.
   7 - 1 = 6
4. Decide. So the stick is 6 cm long, not 7 cm.
   No

Check. Count the centimetres from 1 to 7: 6 of them. ✓

Watch out. Take the start away from the end when the line does not start at 0.