what a (something)

What a ___" communicates the idea "That's really ___" or "You're really ___." Here are some examples:

If you have to throw away food that's still good, you can say:

What a waste, huh?

Here's something a woman can say when a man opens a door for her:

What a gentleman! Thank you very much.

If a lot of people show up to your event or party:

What a great turnout!

Wow!

"Wow!" expresses excitement. You say it when someone tells you something or shows you something. You can use "wow" to express a variety of emotions about the thing you're being told or shown:

• it's interesting and exciting
• you want to encourage the person, especially a child
• you can't think of anything else to say

a big boy / a big girl

You can encourage young children by calling them a "big boy" or "big girl" when they do something impressive for their age like:

• sitting upright without help for the first time
• using the toilet correctly
• cleaning up their toys

You can use this phrase with a child until about age 4. After that, most children feel like they're already a "big boy" or "big girl", so they don't want to be called that.

Calling an adult a "big boy" or "big girl" has a completely different meaning. It means that they're fat.