NCERT Ganita Prakash, Class 6, textbook pages 107–128

How to teach Class 6 Maths Chapter 5, Prime Time, at home

Factors, multiples, primes and divisibility, taught with things you already have at home: a 20-minute activity, a game for the week, a 5-day plan and the mistakes to watch for.

602302153560 = 2 × 2 × 3 × 5

NCERT Class 6 Maths Chapter 5 Prime Time: what it teaches

Your child finds common multiples and factors, identifies prime and composite numbers using the Sieve of Eratosthenes, learns co-prime numbers, writes prime factorisations, and uses divisibility tests for 2, 3, 4, 5, 6, 8, 9, 10 and 11.

Why it matters later. Primes and factorisation lead to HCF, LCM, fractions and algebra in Classes 7 to 10.

See it: this chapter in pictures

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950primes to 50 (yellow)
The sieve leaves only primes.
7128÷2 ✓ ends in 8÷4 ✓ 28 ÷ 4÷8 ✓ 128 ÷ 8÷9 ✓ digits sum 18divisibility tests
Tests avoid long division.
8 and 15factors: 1,2,4,8 | 1,3,5,15only 1 in common → co-prime
Co-prime: only common factor is 1.

You need

  • a 1–100 chart
  • coloured pencils
  • paper for factor trees

Tonight’s 20 minutes

  1. On the 1–100 chart, cross out multiples of 2, 3, 5 and 7 (not the numbers themselves). What’s left are primes.
  2. Make factor trees for 60 and 84.
  3. Test 7,128 for divisibility by 2, 3, 4, 8 and 9 using the rules.
  4. Play the Idli-Vada game: count up, say idli for multiples of 3, vada for multiples of 5.

Words to use

  • prime
  • composite
  • co-prime
  • factor
  • multiple
  • prime factorisation
  • divisible

Watch for

  • Calling 1 a prime number. A prime has exactly two factors; 1 has only one.
  • Stopping a factor tree too early. Keep splitting until every branch ends in a prime.

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouIs 51 prime?

Your childIt looks prime.

YouDigit sum?

Your child6. So divisible by 3: 51 = 3 × 17.

YouFactor tree for 60?

Your child2 × 2 × 3 × 5.

A game for this week: Idli-Vada

  1. Count up in turns from 1.
  2. Say idli for multiples of 3, vada for multiples of 5, idli-vada for both.
  3. A mistake means you’re out.
  4. Last player in wins.

A 5-day plan, 20 minutes a day

  1. Day 1Sieve of Eratosthenes.
  2. Day 2Factor trees.
  3. Day 3Divisibility rules.
  4. Day 4Co-prime numbers.
  5. Day 5Idli-Vada game.

Everyday moments to practise

  • Packing items in equal boxes.
  • Timings of buses that meet.
  • Codes and passwords.
  • Sharing sweets exactly.

Quick check

Ask these at the end of the week. Tap to see the answer.

Is 51 prime?

No, 51 = 3 × 17.

Prime factorisation of 60?

2 × 2 × 3 × 5.

Is 123 divisible by 3?

Yes, digit sum 6 is divisible by 3.

Ready for the next chapter when your child…

  • Identifies primes to 100.
  • Writes prime factorisations.
  • Uses divisibility tests.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Ganita Prakash (Class 6). See the full Class 6 parent guide for every chapter.

Questions parents ask

Is 1 a prime number?

No. A prime has exactly two different factors.

What are co-prime numbers?

Numbers with no common factor other than 1, like 8 and 15.

What is the divisibility rule for 11?

Alternate sum and difference of digits should be 0 or a multiple of 11.