Up in the air!

Who never heard this idiom?!

This is like very common and very easy to get, I promisse!

Up in the air means to be not decided or not completely developed. 

For example: My aunt doesn't know which school she's gonna study at. That's up in the air.

It is also to be undecided about someone or something. To be uncertain.

For example: Liss didn't tell me she was going to travel that weekend. By the time I asked last time, she told me that was up in the air.

Get??