None There’ll Be
There is a word of letters three,
Add one letter to it and none there’ll be.
What is the word?
One. Add an ‘n’ to get none.
Loud Noise When Changing Its Jacket
What makes a loud noise when changing its jacket, becomes larger but weighs less?
Popcorn.
A Woman in a Boat
There’s a woman in a boat, on a lake, wearing a coat.
If you want to know her name, it’s in the riddle I just wrote.
What’s the woman’s name?
“Theresa” is the woman’s name. (There’s a = Theresa)
An alternative answer is “There”.
Built From Anything You Don’t Like
I’m built from anything you don’t like,
You’re using me right now in fact,
I am one but represent many,
When attacked I’m easily cracked,
I’m created in seconds but live forever
And though you may not understand,
I’ll help you do well but be careful my friend,
Hurt me and you won’t withstand.
What am I?
Character (or characters).
Kids are often told, when dealing with unpleasant things, that it builds character. You’re reading the characters this riddle is written with. In computer science a char is often represented by one byte and can store any character you want.
When politicians have their character besmirched it can swiftly change the voting public’s mind about them. Characters in novels are created with a few lines but live on in our memories. And if your character or reputation is damaged, you may find it hard to deal with the aftermath.
And here’s a great quote from Warren Buffet on your character.
“It takes 20 years to build a reputation and five minutes to ruin it. If you think about that, you’ll do things differently.” — Warren Buffet
I Always Send You In The Right Direction
I always send you in the right direction,
I’m arrayed in black and white,
Ignore me and lose my protection,
No more than two words are in sight.
What am I?

A one way street sign. It tells you the correct way to go, is black and white (in the United States), going the wrong way can get you a citation and the sign only has two words on it.
A Final Screech
I saw a strange creature,
Long, hard, and straight,
Thrusting in a round, dark, opening,
Preparing to discharge its load of lives,
Puffing and squealing noises accompanied it,
Then a final screech as it slowed and stopped.
Note: This may not be appropriate for younger ages.
A subway train.