CBSE Class 6 Science – Chapter Wise NCERT Study Materials

Case 1 — Measuring a Classroom Board

Ria measures the length of the classroom board using a metre scale and finds it to be 2.5 m.

Q1. Express the board length in centimetres.

A1. 2.5 m = 2.5 × 100 = 250 cm.

Case 2 — Measuring a Ribbon

Arjun wants to measure a ribbon that is curved. He uses a thread to trace the ribbon and then measures the thread with a ruler.

Q2. Why is the thread method useful?

A2. The thread follows the curve exactly; straightening the thread converts the curved path into a straight length that can be measured accurately with a ruler.

Case 3 — Tape Measure Use

Meera measures the girth of a tree using a measuring tape but notices the tape sags slightly.

Q3. How will sagging affect the measurement and how can she reduce the error?

A3. Sagging increases the measured length, giving an overestimate. To reduce error, Meera should keep the tape taut and level, and take multiple readings to average.

Case 4 — Measuring a Long Wall

A wall is longer than a single ruler. Ravi measures in parts: first 90 cm, then 60 cm.

Q4. What is the total length of the wall?

A4. Total = 90 cm + 60 cm = 150 cm = 1.5 m.

Case 5 — Stopwatch Timing

Students time how long a toy car takes to travel 4 m. Trial times are 2.0 s, 2.1 s and 1.9 s.

Q5. Find the average time and the average speed in m/s.

A5. Average time = (2.0+2.1+1.9)/3 = 6.0/3 = 2.0 s. Average speed = distance/time = 4 m / 2.0 s = 2.0 m/s.

Case 6 — Unit Conversion

A cyclist covers 15 km in one hour.

Q6. What is the cyclist's speed in km/h and in m/s?

A6. Speed = 15 km/h. To convert to m/s: 15 × (1000 m / 3600 s) = 15 ÷ 3.6 ≈ 4.17 m/s.

Case 7 — Measuring Small Objects

Teacher asks students to measure a small insect and one student records 12 mm.

Q7. Express 12 mm in cm and explain which unit is preferable for insects.

A7. 12 mm = 1.2 cm. Millimetres (mm) are preferable for tiny objects because they give finer precision.

Case 8 — Trundle Wheel

A trundle wheel has circumference 1 m. It is rolled 23 full turns across the playground.

Q8. What distance was measured?

A8. Distance = turns × circumference = 23 × 1 m = 23 m.

Case 9 — Ruler Reading Error

Priya placed the ruler's edge at the start but didn't check the zero mark and recorded 2.3 cm.

Q9. What mistake might she have made and how to avoid it?

A9. Ruler edges can be imperfect; she should align the object with the zero mark and not the physical edge. Always check that the measurement starts at 0.

Case 10 — Measuring Diagonal

To find the diagonal of a rectangular book, a student uses a ruler from one corner to the opposite corner and obtains 28 cm.

Q10. What does this 28 cm represent?

A10. It represents the straight-line distance between opposite corners (the diagonal) of the book, not the perimeter or side length.

Case 11 — Speed Comparison

Anil runs 400 m in 80 s while Sunita runs the same distance in 100 s.

Q11. Who is faster and by how much (m/s)?

A11. Anil's speed = 400/80 = 5.0 m/s. Sunita's speed = 400/100 = 4.0 m/s. Anil is faster by 1.0 m/s.

Case 12 — Partial Turns on Trundle Wheel

A trundle wheel of circumference 0.5 m makes 10 full turns and a half turn.

Q12. What is the total distance measured?

A12. Distance = (10 × 0.5) + (0.5 × 0.5) = 5 + 0.25 = 5.25 m.

Case 13 — Converting Units in Classroom

The school ground is 5000 m long along one side.

Q13. Express this length in kilometres.

A13. 5000 m = 5000 ÷ 1000 = 5 km.

Case 14 — Average Speed Over Two Legs

A toy car moves 10 m in 2 s and then 20 m in 4 s.

Q14. What is the average speed over the whole journey?

A14. Total distance = 30 m; total time = 6 s. Average speed = 30 ÷ 6 = 5 m/s.

Case 15 — Estimating Between Marks

On a ruler with mm marks, the length falls slightly beyond 54 mm; student estimates 54.6 mm.

Q15. Is this an acceptable practice and why?

A15. Yes — estimating to a fraction of the smallest division (here tenths of mm) increases precision; record as 54.6 mm and mention it's estimated if required.

Case 16 — Mixing Units

A problem gives distance in metres and time in minutes. Student calculates speed without conversion.

Q16. Why is this incorrect and how should it be fixed?

A16. Units must be consistent. Convert minutes to seconds (or metres to kilometres) before dividing. For example, 120 m in 2 min → time = 120 s; speed = 120 m / 120 s = 1 m/s.

Case 17 — Using a Digital Measure

A digital measuring device shows 1.234 m for a plank length.

Q17. Express this reading in cm and explain precision advantage.

A17. 1.234 m = 123.4 cm. Digital readouts often give more precise values and reduce human reading errors; they show values beyond the smallest marked division for better accuracy.

Case 18 — Recording Units

Suresh writes a measurement as "45" without units in his lab notes.

Q18. Why is this insufficient and what must he do?

A18. Without units the number is ambiguous. Suresh should add the unit (e.g., 45 cm or 45 m) and ensure consistency across calculations.

Case 19 — Measuring a Curve on Map

A student uses a small piece of thread to trace a winding path on a map and then measures the thread to find the path length on the map.

Q19. How can the map distance be converted to real distance if scale is 1 cm = 2 km?

A19. Measure thread length on map in cm (say x cm). Real distance = x × 2 km. Example: if x = 3 cm then real distance = 6 km.

Case 20 — Practical Experiment Planning

Teacher asks students to design an experiment to measure the speed of a rolling ball across 5 m using a stopwatch.

Q20. Outline the steps students should take and the key points to ensure accuracy.

A20. Steps: (1) Mark start and end points 5 m apart. (2) Release the ball without pushing. (3) Use a stopwatch to time from release to crossing end mark. (4) Repeat several trials. (5) Calculate speed = distance/time for each trial and average. Key points: keep surface level, use same release point, start/stop timing precisely, repeat trials and record units.

CBSE Class 6 Science — Chapter 5: Measurement of Length and Motion

Case-based Questions — Practice & Application

Case 1 — Measuring a Classroom Board

Case 2 — Measuring a Ribbon

Case 3 — Tape Measure Use

Case 4 — Measuring a Long Wall

Case 5 — Stopwatch Timing

Case 6 — Unit Conversion

Case 7 — Measuring Small Objects

Case 8 — Trundle Wheel

Case 9 — Ruler Reading Error

Case 10 — Measuring Diagonal

Case 11 — Speed Comparison

Case 12 — Partial Turns on Trundle Wheel

Case 13 — Converting Units in Classroom

Case 14 — Average Speed Over Two Legs

Case 15 — Estimating Between Marks

Case 16 — Mixing Units

Case 17 — Using a Digital Measure

Case 18 — Recording Units

Case 19 — Measuring a Curve on Map

Case 20 — Practical Experiment Planning

Measurement of Length and Motion – Case-based Questions with Answers

CBSE Class 6 Science — Chapter 5: Measurement of Length and Motion

Case-based Questions — Practice & Application

Case 1 — Measuring a Classroom Board

Case 2 — Measuring a Ribbon

Case 3 — Tape Measure Use

Case 4 — Measuring a Long Wall

Case 5 — Stopwatch Timing

Case 6 — Unit Conversion

Case 7 — Measuring Small Objects

Case 8 — Trundle Wheel

Case 9 — Ruler Reading Error

Case 10 — Measuring Diagonal

Case 11 — Speed Comparison

Case 12 — Partial Turns on Trundle Wheel

Case 13 — Converting Units in Classroom

Case 14 — Average Speed Over Two Legs

Case 15 — Estimating Between Marks

Case 16 — Mixing Units

Case 17 — Using a Digital Measure

Case 18 — Recording Units

Case 19 — Measuring a Curve on Map

Case 20 — Practical Experiment Planning

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