Class 6 Science · Original EZT practice
Measurement of Length and Motion (Class 6 Chapter 5): summary and practice
How long is your desk - in handspans or in centimetres? Chapter 5 starts with why the world needed standard units, how to measure a length correctly, how to describe where something is, and how to tell apart the ways things move - straight, round and round, or to and fro. All questions are original EZT tutor practice following the chapter's own section order. Edition note: this page covers the new NCERT book Curiosity (Grade 6). If your Class 6 book is the older edition, your chapter 5 was Separation of Substances and motion/measurement was chapter 10 - check your chapter title, not just the number.
8 original worked examples, 8 fresh self-check questions and 4 mixed questions, with explained answers. These are not copied textbook exercises, an official chapter index or a full answer key. No affiliation with NCERT is claimed.
Official sources for topic and edition context, checked 20 October 2026:
1. Why standard units
Measuring with body parts gives different answers for different people - a teacher's handspan is not a child's. When people started travelling and trading, such confusion pushed countries to come together and adopt a set of standard units. Today the standard unit of length is the METRE (m), with the kilometre (km) for large distances, and the centimetre (cm) and millimetre (mm) for small ones.
2. Converting between units
The ladder: 1 kilometre = 1000 metres; 1 metre = 100 centimetres; 1 centimetre = 10 millimetres. To go from a bigger unit to a smaller one, multiply; from smaller to bigger, divide.
3. The correct way to measure length
A scale can lie to you if you use it carelessly. Place the scale along the object, straight and touching it. Check the zero end - if it is worn or broken, start from another full mark and subtract. And your eye must be directly above the mark you are reading - viewing from the side shifts the reading (this error is called parallax).
4. Describing position and types of motion
To say WHERE something is, describe its position against a reference object. To say HOW it moves, watch its path: a dropped eraser, a falling orange, a march-past column and a pushed box all move along a straight line - rectilinear motion. A point on a spinning wheel or a ceiling-fan blade goes round and round - circular motion. A swing or a pendulum moves to and fro about a fixed position - oscillatory motion. Some objects mix types: a rolling ball's centre goes straight while points on it go in circles.
Choose, solve, check, then try a fresh question.
Before calculating, read the method prompt and name the condition that makes it useful. Write your own attempt. Open the steps only when you need them, and use the check to catch a wrong sign, unit or interpretation. Finish with the fresh question before reading its answer.
Explain why standard units were needed
Choose the method: Ask what goes wrong when everyone measures differently, then how agreement fixes it.
EZT practice question
Why did different countries have to agree on standard units?
Show the worked solution
- Body-based and local units differed from person to person and place to place.
- The differences caused confusion - especially once people travelled and traded.
- A common set of units was adopted so measurements agree everywhere.
Answer: Body-based and local units differed from person to person and place to place, causing confusion - especially once people travelled and traded - so a common set of units was adopted.
Check: The answer names both the problem (differing units) and the fix (agreement on standard units).
Watch for this: Do not say units were standardised for convenience alone; confusion in travel and trade forced the change.
Now try it yourself
What is the standard unit of length?
Check your answer
The metre.
The chapter names the metre (m) as the standard unit of length.
Choose the right unit for a length
Choose the method: Match the size of the object to the size of the unit: mm and cm for small, m for medium, km for large.
EZT practice question
Which unit suits each: (a) length of a pencil, (b) height of a door, (c) distance between two cities, (d) thickness of a coin?
Show the worked solution
- A pencil is a few centimetres long - use centimetres.
- A door is about two metres - use metres.
- Cities are far apart - use kilometres.
- A coin is very thin - use millimetres.
Answer: (a) centimetres, (b) metres, (c) kilometres, (d) millimetres.
Check: Each unit matches the scale of what is being measured.
Watch for this: Do not measure a city-to-city distance in metres; large distances call for kilometres.
Now try it yourself
Why is a handspan a poor unit?
Check your answer
It varies from person to person.
A teacher's handspan is not the same as a child's, so measurements disagree.
Convert metres to centimetres
Choose the method: Bigger unit to smaller unit: multiply by 100.
EZT practice question
Convert 2.5 m to centimetres.
Show the worked solution
- 1 m = 100 cm, so multiply by 100.
- 2.5 x 100 = 250.
Answer: 250 cm.
Check: 250 cm = 250 / 100 = 2.5 m - back-conversion agrees.
Watch for this: Do not divide; going from a bigger unit to a smaller one needs multiplication.
Now try it yourself
How many millimetres are there in 15 cm?
Check your answer
150 mm.
1 cm = 10 mm, so 15 x 10 = 150.
Convert between units in both directions
Choose the method: Bigger to smaller: multiply. Smaller to bigger: divide.
EZT practice question
Convert 3400 m to kilometres and 7 cm to millimetres.
Show the worked solution
- 3400 / 1000 = 3.4 km (smaller to bigger: divide).
- 7 x 10 = 70 mm (bigger to smaller: multiply).
Answer: 3.4 km and 70 mm.
Check: 3.4 km = 3400 m and 70 mm = 7 cm - both back-conversions agree.
Watch for this: Do not multiply when going to a bigger unit; that direction needs division.
Now try it yourself
How many metres are there in 6 km?
Check your answer
6000 m.
1 km = 1000 m, so 6 x 1000 = 6000.
Measure with a broken scale
Choose the method: Start from any full mark and subtract that mark from the end reading.
EZT practice question
A pencil's ends line up with the 2 cm and 11 cm marks on a broken scale. What is its length?
Show the worked solution
- The zero end is unusable, so the measurement starts at 2 cm.
- Subtract: 11 - 2 = 9.
Answer: 9 cm - subtract the starting mark when the zero end is unusable.
Check: 9 cm is the distance between the two marks, which is the pencil's true length.
Watch for this: Do not report 11 cm; that counts the 2 cm before the pencil's starting end.
Now try it yourself
What is parallax error?
Check your answer
A wrong reading caused by viewing the scale from an angle instead of straight above.
Viewing from the side shifts the apparent position of the mark.
Explain the correct eye position
Choose the method: Ask what happens to the reading when the eye moves to the side.
EZT practice question
Why must the eye be directly above the mark while reading a scale?
Show the worked solution
- Viewing from the side shifts the apparent position of the mark against the object.
- That shift gives a wrong reading - a parallax error.
- Placing the eye directly above removes the shift.
Answer: Reading from the side shifts the apparent position of the mark against the object - a parallax error - giving a wrong reading.
Check: The answer names the shifted reading as parallax error.
Watch for this: Do not blame the scale; the error comes from the viewing angle, not the instrument.
Now try it yourself
What do you do if the zero mark of a scale is broken?
Check your answer
Measure from another full mark and subtract it.
Subtracting the starting mark gives the true length.
Classify types of motion
Choose the method: Watch the path: straight line is rectilinear, round and round is circular, to and fro is oscillatory.
EZT practice question
Classify: (a) an orange falling from a tree, (b) a ceiling fan's blade, (c) a swing.
Show the worked solution
- The orange falls along a straight line - rectilinear.
- The fan blade goes round and round - circular.
- The swing moves to and fro about a fixed position - oscillatory.
Answer: (a) rectilinear, (b) circular, (c) oscillatory.
Check: Each example matches the path shape of its motion type.
Watch for this: Do not call a swing circular; it moves to and fro, not round and round.
Now try it yourself
Define rectilinear motion.
Check your answer
Motion along a straight line.
That is the chapter's definition of rectilinear motion.
Identify the motion in a march-past
Choose the method: Trace the path the soldiers move along.
EZT practice question
Soldiers in a Republic Day march-past move in which type of motion?
Show the worked solution
- The soldiers move forward along a straight-line path.
- Motion along a straight line is rectilinear.
Answer: Rectilinear - they move along a straight-line path.
Check: The path is straight, which is the defining test for rectilinear motion.
Watch for this: Do not call it oscillatory; the soldiers do not move to and fro about a fixed position.
Now try it yourself
Which type of motion does a pendulum show?
Check your answer
Oscillatory - to and fro about a fixed position.
A pendulum swings back and forth around its mean position.
Try a mixed set
Choose a method or explanation before opening each answer.
1. What is the standard unit of length?
Show answer and reason
The metre (m).
It was adopted worldwide so measurements agree everywhere.
2. How many centimetres make 1 metre?
Show answer and reason
100.
The ladder runs 1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm.
3. Which type of motion does a swing show?
Show answer and reason
Oscillatory.
It moves to and fro about a fixed position.
4. What is parallax error?
Show answer and reason
A wrong reading from viewing the scale at an angle.
The eye must be directly above the mark being read.
Try it yourself
Work these on paper before checking any notes. Answers are deliberately not shown here.
- Convert 4.2 km to metres, and 56 mm to centimetres.
- Your scale's zero end is broken and a ribbon measures from the 3 cm mark to the 20 cm mark - how long is the ribbon?
- Name the type of motion of (a) a ceiling fan blade, (b) a dropped eraser, (c) a pendulum.
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Questions about this practice page
- What is the standard unit of length?
- The metre (m) - adopted worldwide so that measurements agree everywhere. 1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm.
- What is parallax error?
- A wrong scale reading caused by viewing the mark from the side instead of directly above it.
- How do you measure with a broken scale?
- Start from any full mark and subtract that mark from the end reading (11 - 2 = 9 cm).
- Name the three types of motion with one example each.
- Rectilinear (falling orange), circular (fan blade), oscillatory (swing or pendulum).
- Are these the NCERT exercise questions for Measurement of Length and Motion?
- No. EZT pages are original practice written by our tutors, aligned to the chapter's syllabus - use them to prepare for the textbook exercises, not as a substitute for your book.