What always comes into a house through the keyhole?

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

I want to fill my bucket using both cold and hot water.
I have two taps for both cold and hot water. The hot water tap fills the bucket in exact 6 hours and the cold water tap fills the bucket in exact 4 hours.
I turn both of them simultaneously but I forgot to turn off another tap which removes the water out of the bucket. This tap can empty the bucket in 12 hours.

How Long will it take to fill the bucket?

I can write cow in 13 letters.

Can You?

Can you spot the hidden clock in this family photo? Only the most eagle-eyed will find it!

We can be boring,Or interesting.
We can be long,Or short.
We can have pictures,Or just words.
Many love us,But many also hate us.
What are we?

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

If EELS + MARK + BEST + WARY = EASY

What does HELP + BARK + WARD + LEAD equal?

The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.

What can a student say to prevent his being expelled from school?

People put me on the table and cut me but do not eat me. What am I?