Chapter 4: Vacation with My Nani Maa

Summer holidays at Nani Maa's village are full of cows, fields and adventures. They are also full of measurement! How tall is the mango tree? How long is the rope swing? Let's find out.

What we'll learn

Compare the lengths of two things by looking.
Measure using handspans, footsteps, sticks and threads.
Understand why everyone needs the same unit.
Estimate length before measuring.
Use words like longer, shorter, taller, deeper.

The big idea

Before rulers existed, people used their own bodies to measure. A handspan is the gap between your stretched thumb and little finger. A footstep is the length from heel to heel of your stride. These are called non-standard units because they change from person to person.

Nani Maa's handspan is bigger than yours. If she says the cot is "5 handspans long" and you measure the same cot, you might get 7 handspans. Both are correct , but they sound different. That is confusing.

To avoid confusion, people invented standard units like centimetres and metres. A metre is the same length in Delhi, Chennai or Shillong. That is why your school ruler shows centimetres and not handspans.

Estimating first is a wonderful habit. Before measuring the length of your bed, guess. Then measure. The more you practice, the better your guesses become.

Let's explore

Handspan hunt. Use your handspan to measure 5 things , your desk, a book, a bedsheet, the door, a chair. Write each length down.

Pair check. Get a friend or family member to measure the same 5 things with their handspan. Compare answers. Why are they different?

Thread map. Take a long thread. Place it along the curving boundary of a leaf or a stone. Then straighten the thread and measure it with a ruler. That is how curvy things are measured.

Estimate then check. Guess how many of your footsteps cover the length of your room. Then walk and count. How close were you?

Worked examples

Example 1. Sneha measures her notebook. It is 4 handspans long. Her brother measures the same notebook and gets 5 handspans. Why?

Their handspans are different sizes.
Sneha's handspan is longer, so she needs fewer.
Her brother's handspan is shorter, so he needs more.

Example 2. A rope is 3 metres long. A stick is 1 metre long. How many sticks long is the rope?

3 metres ÷ 1 metre = 3.
The rope is 3 sticks long.

Example 3. Estimate then count. Riya guesses the table is 6 handspans wide. She measures and gets 8. What is the difference?

8 − 6 = 2.
She was off by 2 handspans.

Quick check

Which is longer: your foot or your handspan?
Why do we need standard units like centimetres?
Name 3 things you can measure with a thread.
A sari is 5 metres long. A shawl is 2 metres. How much longer is the sari?
Estimate the length of your pencil in centimetres, then measure.

Recap

Length can be measured with body parts, sticks or threads.
Non-standard units change from person to person.
Standard units like the metre help everyone agree.