Answer:
What can be measured but not seen?
I can be short and sometimes hot. When displayed, I rarely impress.
What is that over the head and under the hat?
You need a key to receive an answer from me. The answer you'll find is straight from your mind. What is it?
Three little letters, a paradox to some. The worse that it is, the better it becomes.
What is so fragile that saying its name breaks it?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?