Estimating and Comparing Weight

Estimation: A brick ≈ 1 kg, so 2 bricks ≈ 2 kg. Feather ≈ 0.01 g. Coin ≈ 8 g. Mobile phone ≈ 200 g. Comparing: Which is heavier: 3 kg of cotton or 3 kg of iron? TRICK QUESTION! Both are 3 kg. Weight depends on amount, not material. 3 kg = 3 kg regardless of material. Cotton just takes up more space (less dense).