Measuring Length

Given: The picture shows students measuring the depth of something (e.g., a well or container).

From the picture, the students are measuring depth.

Tick marks (✓):
- a) Length ✓ (depth is a form of length measurement)
- b) Height ✓ (height is also a form of length measurement)
- c) Weight ☐ (not being measured)
- d) Depth ✓ (already ticked — this is what is directly shown)
- e) Breadth ✓ (breadth is also a form of length measurement)
- f) Temperature ☐ (not being measured)

Note: As the teacher's note explains, height, width, depth, and breadth all refer to length measurement. So length, height, breadth, and depth can all be ticked.

Given: The picture shows students measuring height.

Answer:
A measuring tape (or metre scale/metre rope) is being used to measure the height in the picture.

Other tools that can be used to measure height:
1. A metre scale (ruler)
2. A metre rod
3. A measuring tape used by tailors
4. A metre rope

All these tools help us find out how tall (high) something is.

Given: We need to check each statement against real classroom observations. (Answers may vary; typical expected answers are given below.)

Concept: 1 metre = 100 cm. Average height of Class 4 students ≈ 120–140 cm (more than 1 m). Arm length ≈ 50–60 cm (less than 1 m). Door height ≈ 200 cm (more than 1 m). Blackboard breadth ≈ 150–200 cm (more than 1 m).

a) The height of most of the students in my grade is more than a metre. → Correct (Most Class 4 students are taller than 1 m.)

b) The length of my arm is less than a metre. → Correct (An arm is usually about 50–60 cm, which is less than 100 cm = 1 m.)

c) The height of the door of the grade is less than a metre. → Incorrect (A standard door is about 2 m tall, which is more than 1 m.)

d) The breadth of the blackboard is more than a metre. → Correct (A classroom blackboard is usually more than 1 m wide.)

Given: We have a 1 m rope.

How to make the lines:
- 1 m line: Place the 1 m rope on the floor and draw a line along it. This gives a 1 m line.
- 5 m line: Place the 1 m rope end-to-end 5 times on the floor, marking each end. Join the marks to get a 5 m line.
- 10 m line: Place the 1 m rope end-to-end 10 times on the floor, marking each end. Join the marks to get a 10 m line.

Activity: Walk, jump, and crawl along each line to get a feel for how long 1 m, 5 m, and 10 m are.

*This is a hands-on activity. Results will vary for each student.*

Given: Students perform a long jump and measure the distance using 1 m, ½ m, and ¼ m ropes.

How to measure:
- After each jump, place the 1 m rope from the starting line to where the student landed.
- If the distance is more than 1 m, use the 1 m rope first, then use the ½ m or ¼ m rope for the remaining part.
- Record whether the jump is less than 1 m, equal to 1 m, or more than 1 m.

Sample filled table (answers will vary for each class):

| Name of the student | Less than 1 m | 1 m | More than 1 m | Actual measurement |
|---|---|---|---|---|
| Riya | | | ✓ | 1 m and ¼ m |
| Amit | ✓ | | | ¾ m |
| Priya | | ✓ | | 1 m |

*Students should fill in their own classmates' names and measurements.*

Given: We need to estimate and then measure the length and breadth of the classroom.

How to measure:
- Use the 1 m rope repeatedly along the length of the classroom, counting how many times it fits.
- Do the same for the breadth.

Sample answer (will vary by classroom):
- Estimated length of classroom: about 8 m
- Actual length of classroom: 8 m (measured using the 1 m rope 8 times)
- Estimated breadth of classroom: about 6 m
- Actual breadth of classroom: 6 m (measured using the 1 m rope 6 times)

*Students should record their own classroom's measurements.*

Given: Pictures of a bus and a cricket bat are shown (images not visible, but standard sizes are used).

Standard lengths:
- Length of one bus ≈ 12 metres (a standard city bus is about 12 m long)
- Length of one cricket bat ≈ 1 metre (a standard cricket bat is about 96 cm ≈ 1 m)

Answer:
- Length of one bus = approximately 12 m
- Length of one cricket bat = approximately 1 m

*(Answers may vary slightly depending on the values given in the pictures in the textbook.)*

Given: (Based on typical textbook values)
- Length of one blue whale ≈ 30 m
- Length of two blue whales = 30 × 2 = 60 m
- Length of one bus ≈ 12 m

Calculation:
$$\text{Number of buses} = \frac{60}{12} = 5$$

Answer: 5 buses would be equal to the length of two blue whales.

*(Note: If the textbook uses different values for bus/whale length, apply the same method with those values.)*

Given: (Based on typical textbook values)
- Length of one blue whale ≈ 30 m
- Length of one cricket bat ≈ 1 m

Calculation:
$$\text{Number of cricket bats} = \frac{30 \text{ m}}{1 \text{ m}} = 30$$

Answer: 30 cricket bats will be needed to measure one whale.

*(Apply the same method if the textbook gives different values.)*

Given: (Based on typical textbook values)
- Height of one ostrich ≈ 2.5 m
- Height of two ostriches stacked = 2.5 × 2 = 5 m

Looking at the picture clues, two ostriches stacked would be equal to the height of a giraffe (a giraffe is about 5 m tall).

Answer: If two ostriches stand one above another, their height will be equal to the height of a giraffe.

*(Answer depends on the picture values given in the textbook.)*

Given: (Based on typical textbook values)
- Length of one blue whale ≈ 30 m
- Length of one crocodile ≈ 5 m

Calculation:
$$\text{Number of crocodiles} = \frac{30}{5} = 6$$

Answer: 6 crocodiles will be equal to the length of a blue whale.

*(Apply the same method if the textbook gives different values for crocodile length.)*

Given: 1 metre (m) = 100 centimetre (cm)

**Finding $\frac{1}{2}$ m in cm:**
$$\frac{1}{2} \text{ m} = \frac{1}{2} \times 100 \text{ cm} = 50 \text{ cm}$$

**Finding $\frac{1}{4}$ m in cm:**
$$\frac{1}{4} \text{ m} = \frac{1}{4} \times 100 \text{ cm} = 25 \text{ cm}$$

Answer:
$$\frac{1}{2} \text{ m} = \boxed{50} \text{ cm}, \quad \frac{1}{4} \text{ m} = \boxed{25} \text{ cm}$$

Given: Various objects are shown in the pictures (images not visible, but the method is described).

How to measure:
- Place the object along the scale starting from the 0 cm mark.
- Read the measurement at the other end of the object.
- Record the length in cm.

To write in increasing order:
- Measure each object and note its length.
- Arrange from the shortest (smallest cm) to the longest (largest cm).

Example (actual measurements will depend on the pictures):
If the objects are a pencil (10 cm), an eraser (4 cm), a sharpener (2 cm), and a crayon (7 cm), then increasing order would be:
$$\text{Sharpener (2 cm) < Eraser (4 cm) < Crayon (7 cm) < Pencil (10 cm)}$$

*Students should measure the actual objects shown in their textbook and write the order accordingly.*

Given: We need to estimate and then measure each item.

Concept: 1 cm is the length of one small division on a ruler. It is roughly the width of a fingernail.

Expected answers (typical values; actual measurements may vary):

| Length of items | Equal to 1 cm | More than 1 cm | Less than 1 cm | Actual measurement |
|---|---|---|---|---|
| A fingernail | ✓ | | | ≈ 1 cm |
| An eraser | | ✓ | | ≈ 4–5 cm |
| An ant | | | ✓ | ≈ 0.5 cm |
| A grain of wheat | | | ✓ | ≈ 0.6 cm |
| A rajma seed | | ✓ | | ≈ 1.5 cm |

Examples of things less than or equal to 1 cm:
- A grain of rice
- A sesame seed (til)
- An ant
- A mustard seed

*Students should verify by actually measuring with a scale.*

Given: Three toy cars are rolled down a ramp and the distance each travels is measured.

How to measure:
- Place the measuring tape from the bottom of the ramp to where the car stops.
- Read the measurement in cm.
- Rank: Car that travels the farthest = Rank 1; shortest distance = Rank 3.

Sample answer (actual values will vary):

| Car | Distance from the ramp | Rank |
|---|---|---|
| Car 1 | 45 cm | 2 |
| Car 2 | 60 cm | 1 |
| Car 3 | 30 cm | 3 |

*Students should fill in their own measured values.*

Given: A treasure hunt map is shown on a dot grid where 1 square = 1 cm (images not fully visible).

Method:
- Trace each possible route on the yellow tiles.
- Count the number of 1 cm squares (tiles) along each route.
- The route with the most tiles is the longest route.
- The route with the fewest tiles is the shortest route.

Answer: (Will depend on the actual map in the textbook)
- Count each tile step as 1 cm.
- Add up all the steps for each route.
- Compare and identify the longest and shortest routes.

*Students should trace the routes in their textbook map and count the tiles to find the lengths in cm.*

Given: Students trace their own hand and measure its length.

How to measure:
- Trace your hand on paper with fingers together.
- Place the scale from the bottom of the palm (wrist line) to the tip of the longest finger (middle finger).
- Read the measurement.

Sample answer:
Length of my hand = 15 cm (This will vary for each student; typical range for Class 4 students is 13–17 cm.)

*Students should measure their own hand and write the actual value.*