Riddles for High School Students

I speak without a mouth and hear without ears. What am I?

You measure my life in hours, and I serve by expiring. What am I?

The maker sells me, the buyer never uses me, and the user never knows. What am I?

Which door is safest: flames, sharpshooters, or lions that have not eaten in years?

What has cities without houses and rivers without water?

What occurs once in every minute, twice in every moment, and never in a thousand years?

Forward I am heavy, backward I am not. What am I?

What begins and ends with E but contains one letter?

A boat is filled with people, but you see no single person. Why?

What five-letter word becomes shorter when you add two letters?

A man pushes his car to a hotel and says he is bankrupt. What happened?

What gets bigger the more you take away?

How many times from midnight to midnight can a digital clock show triple digits like 1:11?

I grow without life, need air without lungs, and die in water. What am I?

I turn once to keep outsiders out, and again to keep insiders in. What am I?

I am the argument you defend with evidence. What am I?

I am the shortcut in logic that leads to a bad conclusion. What am I?

I am the test question that rewards careful reading. What am I?

I make two sides defend ideas respectfully. What am I?

I am the study plan before finals week. What am I?

I am the club that answers before the buzzer. What am I?

I am the hidden pattern in a data table. What am I?

I am the first draft that becomes an essay. What am I?

I am the clue room that needs teamwork to exit. What am I?

I am the answer you can prove, not just guess. What am I?

I am the question that sparks a seminar. What am I?

I am the grade-level puzzle with more than one step. What am I?

I am the notebook margin full of possible answers. What am I?

I am the silence before someone says wait, I got it. What am I?

I turn advisory into a logic workout. What am I?