Prime and Composite Numbers

• A prime has exactly two factors: 1 and itself.
• A composite has more than two factors.
• Know that 2 is the only even prime; spot twin primes (intro).

Level 1 — Prime vs composite

Level 2 — Testing small numbers

Is 17 prime? Check division by 2, 3, 4 — none divide exactly → prime.

Is 21 prime? 21 = 3 × 7 → composite.

Level 3 — 2 is special

2 is the only even prime. All other even numbers ≥ 4 are composite (divisible by 2).

Level 4 — Twin primes (intro)

Pairs differing by 2: (3, 5), (5, 7), (11, 13), (17, 19).

Indian context: Sieve of Eratosthenes — ancient method; Indian mathematicians studied number patterns for centuries.

NCERT anchor: Math-Magic 4, Ch 14 — Play with Patterns; Ch 11 — Tables and Shares (rectangular arrays)

Is 29 prime or composite?

Step 1 — Try 2: 29 is odd → not divisible by 2.
Step 2 — Try 3: 2+9=11, not divisible by 3.
Step 3 — Try 5: doesn't end in 0 or 5.
Step 4 — 5²=25 < 29; 7²=49 > 29 — test up to 5 only.
Answer: **29 is prime**

List prime numbers between 10 and 25

Step 1 — Check 11 ✓, 12 ✗, 13 ✓, 14 ✗, 15 ✗, 16 ✗, 17 ✓.
Step 2 — 18–19: 19 ✓; 20–23: 23 ✓.
Answer: **11, 13, 17, 19, 23**

• Is 1 prime? (no)
• Smallest prime number? (2)
• Is 39 prime? (no — 3×13)
• Stretch: Find the only pair of twin primes between 30 and 50. (41 and 43)

Revision tip: Cross out composites on a 1–50 grid using the Sieve method — primes remain unmarked.

Open the Practice tab for graded questions on Prime and Composite Numbers.

• Use the platform-native live simulation or PhET-style tool for this topic (number line, Venn, physics playground, molecule builder, sensor dashboard, etc.).
• Mirror / body / home activity: physically do the concept (count objects, measure, role-play) and photograph or describe for portfolio.
• Voice or text reflection with AI Mentor: explain the concept to a younger student or family member.

• "Explain this concept to a Class 6 student using one real example from an Indian home, school, market, or festival."
• "What is one common mistake students make here, and how would you catch yourself making it?"
• Stretch: "How does this connect to coding, robotics, money, health, environment, or a future career?"

• Complete the core practice + one extension activity (photo, table, short reflection, or mini-project) for base XP + topic badge.
• 5-7 day streak or family discussion note = multiplier + visible artifact in parent/principal dashboard.
• Best real-world application stories (anonymised) featured on class or national leaderboard.

• One hands-on project or measurement using the Drishti kit or household items that makes the concept physical.
• Direct link to at least one Future Skill track (Money Management, Green Tech, Cyber Defenders, Micro-Entrepreneurship, AI Mastery, Sustainable Living, Personality Development).
• Coding extension where relevant (simple script, simulation, or data logging).

This material emphasises experiential "learning by doing", competency (apply/create/analyse), vocational exposure, critical thinking, and multidisciplinary connections. Designed to feed live worlds, AI Mentor (with memory), gamification, robotics, parent analytics, and future skills — not just exam prep.

Portfolio Evidence Idea: Your photo/table/reflection/project + one sentence on "How this helps me in real life or a possible future path."

Open the Practice tab for aligned questions (easy/medium/hard + case-based) with full AI scaffolding.

See curriculum for cross-links and the full future-skills/robotics chapters.