Ready
Set
Go!
100

I'm tall when I'm young and short when I'm old. What am I?

A Candle 

100

What can’t talk on its own but will reply when spoken to?

An Echo

100

If you have me you want to share me, if you share me you won't have me. What am I?

A Secret

200

What word can you add letters to make it shorter?

Short

200

What belongs to you but other people use it more than you do?

Your Name

200

What is always in front of you but can’t be seen?

The Future

300

What is harder to catch the faster you run?

Your Breath

300

What gives you ability to walk through walls?

Doors

300

I start with M, end with X, and I have any number of letters in me. What am I?

A Mailbox 

M
e
n
u