Measuring Length (Grade 2)
Measuring length means finding out how long, how short, or how tall something is. In Class 1, we compared lengths using words like longer and shorter. Now in Class 2, we learn to measure objects using a ruler and standard units like centimetres (cm) and metres (m).
When you measure your pencil, your notebook, or your water bottle with a ruler, you are finding out the exact length. Measurement gives us a number so we can tell others exactly how long something is, instead of just saying "it is long" or "it is short".
Knowing how to measure length is important in daily life. Tailors measure cloth, carpenters measure wood, and builders measure walls. Even when you check how tall you are at the doctor's clinic, length measurement is being used!
What is Measuring Length - Class 2 Maths (Measurement (Grade 2))?
Length is the distance from one end of an object to the other end. It tells us the size of an object along its longest side.
We use two main units to measure length:
- Centimetre (cm) — used for small objects like pencils, erasers, books, and crayons. Your fingernail is about 1 cm wide.
- Metre (m) — used for bigger things like the length of a room, a cricket pitch, or the height of a door. A door is about 2 metres tall.
1 metre = 100 centimetres (1 m = 100 cm)
Think of it this way: if you line up 100 one-centimetre blocks end to end, they would be exactly 1 metre long!
Measuring Length (Grade 2) Formula
How to measure with a ruler (step by step):
- Place the 0 mark of the ruler at one end of the object. Make sure it is exactly at the edge.
- Keep the ruler straight along the object — do not tilt it.
- Look at the other end of the object carefully.
- Read the number on the ruler where the object ends.
- That number (in cm) is the length of the object.
Example: If a crayon starts at 0 and ends at 8 on the ruler, its length is 8 cm.
What if the ruler is broken or you cannot start at 0?
Sometimes the edge of the ruler is worn out, or the object does not start at the 0 mark. In that case, note the starting mark and the ending mark, then subtract.
Length = Ending mark − Starting mark
Solved Examples
Example 1: Example 1: Measuring a Pencil
Question: Ria places her pencil along a ruler. It starts at 0 cm and ends at 15 cm. How long is the pencil?
Think:
- The pencil starts at 0 cm on the ruler.
- It ends at the 15 cm mark.
- Length = 15 − 0 = 15 cm
Answer: The pencil is 15 cm long. That is about as long as the distance from your wrist to the tip of your fingers!
Example 2: Example 2: Measuring a Ribbon (Not Starting at 0)
Question: Aman has a ribbon placed on a ruler. It starts at the 3 cm mark and ends at the 12 cm mark. How long is the ribbon?
Think:
- The ribbon does not start at 0 — it starts at 3 cm.
- It ends at 12 cm.
- We need to subtract: 12 − 3 = 9 cm.
Answer: The ribbon is 9 cm long. Remember: when the object does not start at 0, always subtract the starting number from the ending number.
Example 3: Example 3: Converting Metres to Centimetres
Question: A dining table is 2 metres long. How many centimetres is that?
Think:
- We know that 1 metre = 100 cm.
- So 2 metres = 2 × 100 = 200 cm.
Answer: The table is 200 cm long. Converting metres to centimetres helps us compare lengths measured in different units.
Example 4: Example 4: Choosing the Right Unit
Question: Would you measure the length of a cricket bat in centimetres or metres?
Think:
- A cricket bat is about as long as your arm — not tiny like an eraser, not huge like a room.
- Using centimetres gives us a nice number (about 85 cm).
- Using metres would give 0.85 m — a decimal that is harder for Class 2.
Answer: We measure a cricket bat in centimetres (cm). For objects you can hold in your hands, centimetres are usually the better choice.
Example 5: Example 5: Measuring a Classroom
Question: Priya's classroom is 8 metres long. Her teacher asks her to write this in centimetres. What is the answer?
Think:
- 1 metre = 100 cm.
- 8 metres = 8 × 100 = 800 cm.
Answer: The classroom is 800 cm long. For very large lengths like a classroom or playground, metres are easier to use.
Example 6: Example 6: Measuring with a Broken Ruler
Question: Dev's ruler is broken at the start. The 0 and 1 marks are missing. He places his eraser starting at the 2 cm mark. The eraser ends at the 7 cm mark. How long is the eraser?
Think:
- Start = 2 cm, End = 7 cm.
- Length = End − Start = 7 − 2 = 5 cm.
Answer: The eraser is 5 cm long. A broken ruler still works — just remember to subtract!
Example 7: Example 7: Estimating Before Measuring
Question: Neha guesses that her tiffin box is about 20 cm long. She then measures it with a ruler and gets 18 cm. Was her guess close?
Think:
- Neha's guess = 20 cm.
- Actual measurement = 18 cm.
- Difference = 20 − 18 = 2 cm.
- A difference of 2 cm is quite small — her guess was good!
Answer: Yes, Neha's guess was very close. She was off by only 2 cm. Estimating first and then measuring is a great way to build your measurement skills!
Example 8: Example 8: Measuring Your Hand Span
Question: Arjun spreads his hand wide on a ruler. His thumb is at 0 cm and his little finger reaches 14 cm. What is his hand span?
Think:
- Start = 0 cm, End = 14 cm.
- Hand span = 14 − 0 = 14 cm.
Answer: Arjun's hand span is 14 cm. You can use your hand span to estimate the length of objects when you do not have a ruler handy.
Real-World Applications
Where do we use length measurement in real life?
- At the tailor: The tailor measures cloth in metres and centimetres to stitch clothes that fit perfectly.
- At school: We measure the length of our notebooks, textbooks, and desks.
- In sports: The cricket pitch is 22 yards (about 20 metres) long. Running races are measured in metres.
- At home: Measuring a wall before hanging a picture, or checking if furniture fits in a room.
- At the doctor: Your height is measured in centimetres to track how much you are growing.
Key Points to Remember
- Length tells us how long or short an object is — the distance from one end to the other.
- We use centimetres (cm) for small objects and metres (m) for big things.
- 1 metre = 100 centimetres. To convert metres to cm, multiply by 100.
- Always place the 0 mark of the ruler at one end of the object for accurate measurement.
- If the ruler does not start at 0, subtract the starting number from the ending number to find the length.
- Estimate the length first, then measure to check how close your guess was.
- Keep the ruler straight and aligned with the object while measuring.
Practice Problems
- Measure your pencil using a ruler. Write the length in centimetres.
- A rope starts at the 5 cm mark and ends at the 19 cm mark on a ruler. How long is the rope?
- Convert 3 metres to centimetres.
- Would you use cm or m to measure the length of your school corridor? Explain why.
- Aditi's book is 24 cm long. Kavi's book is 30 cm long. Which book is longer and by how much?
- A cricket pitch is 20 metres long. How many centimetres is that?
Frequently Asked Questions
Q1. What is length?
Length is the distance from one end of an object to the other end. It tells us how long, short, or tall something is. We measure length in centimetres or metres.
Q2. What unit do we use to measure small things?
We use centimetres (cm) to measure small objects like pencils, erasers, books, and crayons. Your fingernail is about 1 cm wide, which gives you an idea of how small a centimetre is.
Q3. How many centimetres are in 1 metre?
There are 100 centimetres in 1 metre. So 1 m = 100 cm. To convert metres to centimetres, multiply the number of metres by 100.
Q4. How do you use a ruler to measure length?
Place the 0 mark of the ruler at one end of the object. Keep the ruler straight. Read the number on the ruler where the other end of the object stops. That number in cm is the length.
Q5. What if my ruler does not start at 0?
Subtract the starting number from the ending number. For example, if an object goes from 3 cm to 10 cm on the ruler, its length is 10 minus 3 = 7 cm.
Q6. When do we use metres instead of centimetres?
We use metres for large things like the length of a room, a playground, a swimming pool, or a road. Metres give smaller, easier numbers for big measurements.
Q7. Why is measuring length important in daily life?
Measuring length is used everywhere — by tailors (stitching clothes), carpenters (cutting wood), builders (constructing rooms), doctors (checking height), and in sports (measuring tracks and pitches).
Q8. What is the difference between length and height?
Length is measured from side to side (horizontally). Height is measured from bottom to top (vertically). Both use the same units — centimetres and metres.
