Class 8 Maths – Chapter 11

Mensuration

STEP 8: Mind Map + Easy Memory Tricks

🧠 MENSURATION – MIND MAP

Mensuration

• 📐 2D Shapes → Perimeter & Area
• 📦 3D Shapes → Surface Area & Volume

2D Shapes:

• Square → Area = side²
• Rectangle → Area = l × b
• Triangle → Area = ½ × b × h
• Circle → Area = πr²

3D Shapes:

• Cube → TSA = 6a², Volume = a³
• Cuboid → TSA = 2(lb + bh + hl), Volume = l × b × h
• Cylinder → CSA = 2πrh, Volume = πr²h

🪄 Easy Memory Tricks

🧊 Cube Trick:

Cube → Think “ALL SIDES SAME” → a³ (easy!)

📦 Cuboid Trick:

l × b × h → Multiply all three different sides

🥫 Cylinder Trick:

Circle + Height → πr²h

⭕ Circle Trick:

πr² → “Pie are square” 😄

📏 Units Memory Trick

• Area → Square units (²)
• Volume → Cube units (³)

Tip: If formula has square → cm² If formula has cube → cm³

🎯 Last-Minute Exam Tip

Read the question carefully → identify shape → write formula → substitute → answer with unit.