Why bubble wrap is so useful

I was very pleased to receive a new mug for my birthday. It came in a bubble wrap parcel. That's because bubble wrap is like a crumple zone. The trapped air in the bubbles crumples up when the parcel is dropped. The crumpling process takes time which means that the change in momentum lasts longer. So the rate of change of momentum is less so the force that would break or scratch my lovely mug is reduced. But that doesn't cover the ideas that Year 10 have been asked to do for their homework. So for the record: If I decided to keep the bubble wrap around the mug when it had a hot drink in, it would act as effective insulation. Air is a bad conductor because the particles are far apart and are not joined. But air is very good at transferring thermal energy by convection. The particles move further apart when they are heated which means that they become less dense than the surrounding air and can thus float upwards. Now if you trap the air in bubbles, you give the air nowhere to go so convection cannot happen. And the trapped air is a bad conductor so it reduces the rate at which thermal energy can leave.