Good Riddles

Question: If you have me, you want to share me. If you share me, you haven't got me. What am I?

Question: I have all of your knowledge but could fit in your hands.

What am I?

Question: Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation.

Note: Each must be used exactly once and no other numbers or symbols can be used.

Question: If you have an 11 minute and 13 minute hourglass, how can you accurately time 15 minutes?

Question: A teacher decides to give a pop quiz one day but all of her students refuse to take the quiz thinking that the teacher will call off the quiz. She can give only one of these students a detention for skipping the quiz. All of the students know each other's names and if a student knows he/she is getting a detention they take the quiz.

How can she threaten her students with the single detention so they all take the quiz?