I am a Y2 refrigeration mechanic, I like this post it gets some basics down quick. I feel however to really get the point across about cold. I feel its good to mention how "cold" is relative to the test item. I like to use a spoon in the fridge and some salted ice water in the freezer. I get somebody to touch the spoon, it feels cold to them then I get them to swirl their finger in the saline water for a couple seconds then touch the spoon again, in most cases the cold fridge spool feels warm to that finger showing that the cold spoon is warm relative to the colder ice water.