Ok, so I was late for work today (as usual), and I had my bacon sandwich in my pocket so that I could eat it when I got there. Anyway, I had wrapped it up in aluminium foil and as I was walking down the road, I thought to myself "was there a better way?". The way I saw it was that metal conducts heat right, so if had a hot bacon butty, then much of the heat would be transferred to the metal and then lost radiated into the surroundings. However if I had my sandwich in a Tupperware container that is an insulator, then the heat would remain in the vicinity of the sandwich. Am I right? If not, which is better for containing a hot substance?