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Class 6 Science: Measurement of Length and Motion, 8 practice questions with answers

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These are 8 practice questions on Class 6 Science Chapter 5, Measurement of Length and Motion, of the new NCERT textbook, Curiosity. Each has a worked answer and the textbook page it comes from. They cover why a length needs a unit, writing units, converting between metres and centimetres, the smallest length a scale can measure, measuring around a curved object with a thread, the reference point, and linear, circular, oscillatory and periodic motion. Try each one on paper before you open the answer.

These questions are our own, drafted with AI help. Every number was re-computed by a test script and none of the numbers is taken from the chapter apart from the chapter's own facts (1 m = 100 cm, 1 cm = 10 mm, the 15-cm scale), but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity: Textbook of Science for Grade 6, Chapter 5, printed pages 79 to 100):

Units and conversions

Question 1. Ankit's handspan is 18 cm. He measures a bench as 9 handspans and tells his sister, "The bench is 9 long." What is missing from his answer? Give the length of the bench in centimetres.

Answer: he gave only a number, with no unit; the bench is about 162 cm. A length has two parts, a number and a unit, so "9 long" does not say 9 of what. Using his handspan as the unit, the bench is 9 handspans, which is 9 × 18 cm = 162 cm. (A length is a number and a unit, page 81.)

Question 2. Rahul writes in his notebook: "The rope is 3 Mtrs. long and the pin is 25 mms." Correct the way he has written the units.

Answer: "3 m" and "25 mm". The symbol for metre is m and for millimetre is mm. The symbols are written in lower case, are never followed by "s" for the plural, have no full stop after them (except at the end of a sentence), and are written with a space after the number. So: "The rope is 3 m long and the pin is 25 mm." (Writing units, page 86.)

Question 3. A ribbon is 2 m 35 cm long. It is cut into equal pieces, each 47 cm long. How many pieces are there?

Answer: 5 pieces. First write the whole length in centimetres: 1 m = 100 cm, so 2 m 35 cm = 200 cm + 35 cm = 235 cm. Then 235 cm ÷ 47 cm = 5. (1 m = 100 cm, page 83.)

Measuring correctly

Question 4. Kavya measures her pencil with a 15-cm scale and writes its length as 8.25 cm. Why can this reading not be right, and what could she write instead?

Answer: the scale cannot measure hundredths of a centimetre; she should write 8.2 cm or 8.3 cm, whichever mark the end is nearer. On a 15-cm scale each centimetre is divided into 10 parts of 1 mm, and 1 mm (0.1 cm) is the smallest length the scale can measure. A reading such as 8.25 cm claims a part of a millimetre, which the scale has no mark for. (The 15-cm scale and the millimetre, page 83.)

Question 5. Simran wants the distance around a round pole. She wraps a thread around it exactly 4 times, marks the thread, straightens it and finds the marked part is 2 m 28 cm long. What is the distance around the pole?

Answer: 57 cm. 2 m 28 cm = 228 cm, and this length goes around the pole 4 times, so once around is 228 cm ÷ 4 = 57 cm. (Measuring a curved length with a thread, page 87; 1 m = 100 cm, page 83.)

Position and motion

Question 6. A straight road runs east to west, and the school is the reference point. Ravi's house is 400 m east of the school and Sita's house is 250 m west of the school. How far apart are the two houses along the road?

Answer: 650 m. The two houses are on opposite sides of the reference point, so the distances add: 400 m + 250 m = 650 m. If both houses had been on the same side, we would subtract instead. Stating each position from one fixed point, the school, is what lets us compare them. (Reference point, page 88.)

Question 7. Asha says, "A sewing machine's needle moves along a straight line, so its motion is linear." Find her mistake.

Answer: the needle moves up and down again and again about a fixed position, so its motion is oscillatory. Linear motion is motion along a straight line. The needle does move along a short straight path, but it keeps going to and fro, up and down, about a fixed position, which is oscillatory motion. (Linear motion, page 92; oscillatory motion, page 93.)

Question 8. Rohan says, "The tip of a clock's second hand keeps moving all the time, so its motion is not periodic." Find his mistake.

Answer: moving all the time does not stop a motion from being periodic; the tip's motion is periodic. A motion is periodic if the object repeats its path after a fixed interval of time. The tip moves along a circular path and goes round the same path again and again, once every minute, so it repeats its path after a fixed interval of time. Circular and oscillatory motions are both periodic in nature. (Circular motion, page 92; periodic motion, page 94.)

Questions students ask

What is the SI unit of length? The metre, with the symbol m. Larger lengths are measured in kilometres (1 km = 1000 m), and smaller ones in centimetres and millimetres (1 m = 100 cm, 1 cm = 10 mm). (Pages 82 and 83.)

What is a reference point? A fixed object or point from which a distance or position is stated, such as a bus stand. Whether something is at rest or in motion also depends on the reference point chosen. (Pages 88, 90 and 91.)

What is the difference between circular and oscillatory motion? In circular motion an object moves along a circular path; in oscillatory motion it moves to and fro about a fixed position. Both repeat themselves, so both are periodic. (Pages 92 to 94.)

Practise more, and check your marks

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Sources

All opened and read on 22 October 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 78.

The facts are from the textbook pages above. The questions, worked answers and checks are our own, and every number was re-computed by script. This guide is general information; follow your teacher and the textbook.