Case Study-Measurement of Length and Motion-Class 6-Science

Case Study 1: Deepa and the Mystery of Measurement

Deepa, an eleven-year-old girl from Haryana, needed a new uniform for school. Her mother took her to a shop where the shopkeeper measured the cloth using a metal measuring rod. At the tailor’s shop, her measurements were taken using a flexible measuring tape. Her mother also asked the tailor to increase the length of her uniform by char angula (four finger widths). Deepa was curious about the different methods of measuring length. She shared her experience with her friends Anish, Hardeep, Padma, and Tasneem, which led to a discussion on how people measure things in different ways.

Questions & Answers:

1. What two measuring tools were used for Deepa’s uniform?
   Answer: A metal measuring rod and a flexible measuring tape.

2. What does ‘char angula’ mean?
   Answer: It means four finger widths, a traditional unit of measurement.

3. Why was Deepa curious about measurement?
   Answer: She saw different measuring tools being used and wanted to understand them better.

4. What did Deepa and her friends discuss?
   Answer: They discussed different methods of measuring length.

5. Why do we need standard units of measurement?
   Answer: Because body-based measurements (like finger width) differ from person to person.

Case Study 2: Measuring Length with Body Parts

Deepa and her friends decided to measure their classroom table using their handspans. They found that the number of handspans varied for each person. Tasneem realized that this happened because everyone’s hands were of different sizes. This made them understand why using body parts for measurement is not reliable. Deepa then concluded that people use scales and measuring tapes to get accurate and uniform measurements. Their teacher explained that in ancient times, people used units like angula (finger width), dhanusa, and yojana for measurement.

Questions & Answers:

1. What method did Deepa and her friends use to measure the table?
   Answer: They used their handspans.

2. Why did their measurements vary?
   Answer: Because everyone’s hand size was different.

3. What did they learn from this activity?
   Answer: They learned that body-based measurements are not reliable.

4. What did people in ancient times use for measurement?
   Answer: They used units like angula (finger width), dhanusa, and yojana.

5. Why do we use measuring scales today?
   Answer: To ensure accurate and consistent measurements.

Case Study 3: Standard Units of Measurement

Deepa and her friends learned about the International System of Units (SI units), which is used worldwide for measurements. The SI unit of length is the metre (m). A metre scale is divided into 100 centimetres (cm), and each centimetre is further divided into millimetres (mm). The teacher also explained that 1 kilometre (km) is equal to 1000 metres, which is used for long distances. They also noticed that some rulers have markings in inches, a unit still used in some places.

Questions & Answers:

1. What is the SI unit of length?
   Answer: The metre (m).

2. How many centimetres are there in one metre?
   Answer: 100 centimetres (cm).

3. What is the smallest unit of length on a standard scale?
   Answer: Millimetre (mm).

4. What unit is used for measuring long distances?
   Answer: Kilometre (km), where 1 km = 1000 m.

5. Why do some rulers have inches marked on them?
   Answer: Inches were traditionally used in some countries and are still in use today.

Case Study 4: Measuring Curved Lines

Anish’s family decorated their house with string lights for a festival. He wondered how they measured the curved verandah. His father used a flexible measuring tape, while his mother used a thread to follow the curve, then measured the thread with a scale. Anish’s teacher later explained that curved lengths cannot be measured with a straight scale and require flexible measuring tools.

Questions & Answers:

1. Why was Anish curious about measurement?
   Answer: He wanted to know how the curved verandah was measured for decorations.

2. What tools did his parents use?
   Answer: A flexible measuring tape and a thread with a scale.

3. Why can’t straight rulers measure curved lines?
   Answer: Because they do not follow the shape of the curve.

4. How can curved lines be measured?
   Answer: Using a thread or a flexible tape.

5. Where else do we need to measure curved lines?
   Answer: In roads, arches, and circular objects like bottles and bangles.

Case Study 5: Motion and Reference Points

Deepa and her friends were excited about a school trip to a garden. They argued about whether the garden was closer or farther than the school. Their teacher explained that their observations were different because each was thinking from their own house. The teacher introduced the concept of a reference point, explaining that distances are always measured from a fixed point, such as a bus stop or school.

Questions & Answers:

1. Why did Deepa and her friends disagree about the garden’s distance?
   Answer: Because they were measuring it from their own houses, not a common point.

2. What is a reference point?
   Answer: A fixed place from which distances are measured.

3. How do kilometre stones on highways use reference points?
   Answer: They show distance from a major city like Delhi or Mumbai.

4. Why is a reference point important?
   Answer: It helps measure distances accurately for everyone.

5. What reference point do maps usually use?
   Answer: Latitude and longitude or a specific location.

Case Study 6: Understanding Motion

While travelling on a bus, Deepa noticed that all passengers were sitting still. However, when she looked outside, the buildings and trees seemed to be moving. She wondered if the passengers were at rest or in motion. Her teacher explained that motion depends on the reference point. If she considered the bus as the reference point, the passengers were at rest. If she considered the ground as the reference point, the bus and passengers were in motion.

Questions & Answers:

1. Why did Deepa think passengers were at rest?
   Answer: Because they were not moving inside the bus.

2. Why did outside objects seem to move?
   Answer: Because the bus was moving relative to the ground.

3. What decides if something is moving or at rest?
   Answer: The reference point.

4. Give an example where motion depends on the reference point.
   Answer: A person sitting in a train sees trees moving outside.

5. If you are on a moving escalator, are you at rest or in motion?
   Answer: It depends on the reference point—rest relative to the escalator, motion relative to the ground.