I told my teacher that I liked riddles and puzzles. As a matter of fact, I introduced him to the Puzzling Stack Exchange! Then, he got a sheet of paper, asked for a pen, and when he found one (I didn't have a pen on me, as usual) he wrote something on it.

I was on my computer, writing my anagram puzzle, when he then handed me the sheet of paper. I looked at it and saw what was written on it. This is what it said:

$$$$ $$\color{red}{\LARGE \rm T\quad I\quad M\quad E}$$ $$\small\color{red}{\rm ABDEFGHIJKLMNOPQRSTUVWXYZ}$$ $$$$

(It was written with a red pen.) I asked him what it meant, and he said it was a riddle. I then said that it wasn't a riddle — it was some kind of enigmatic puzzle. And then he asked if I could figure it out and went to lunch as it was the end of class.

What does it mean? I noticed that the alphabet is missing the letter $\rm C$, and the $\rm B$ looked like a $13$ in his handwriting. Was it some kind of message I had to figure out? Perhaps it said "Time's up" since the word TIME is above (up) the alphabet and a clock only has $12$ hours (not $13$)? I didn't know.

Has anyone seen this puzzle before? Would you like me to upload a picture of the original piece of paper? I am unsure what tags I should include, so they might not help. Also, I don't know the name of the puzzle if it is well-known, so I can't research it.

(True story.)