What month of the year has 28 days?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?

Using Only Five 5's and any mathematical operator make sum as 37

What jumps when it walks and sits when it stands?

By using 'because' continuously three times, can you make an English statement ?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?