Revise GCSE Physics

Question:Why is trapped air a better insulator than just air?

By "trapped air" we mean air that is not able to move around. EG Air bubbles in foam.

If air is prevented from moving, convection cannot occur, which is the main method of heat transfer through gases.

This and the fact of air being a poor conductor of heat because it is a gas, makes trapped air one of the best insulators available.