Sharp or Flat?

[aod20]

How can you tell if a note in a scale is suppose to be a flat or a sharp? I'm to the part where I am learning intervals and when it shows two notes I'm suppose to guess its interval name like a perfect 4th a minor 2nd, etc.. I know a flat is when you lower a note by half a step and a sharp is when you move up a note by half a step, but I still get confused when I try to translate it to the keyboard and guess which specific interval it is. I'm usually off by one it seems.

 

[Bezo]

A key will have either sharps or flats, not both. Check the key signature and name the notes accordingly.

There are some things to look out for though...

Gbmaj/Ebmin has a B#, which is obviously just a C.
G# harmonic and melodic min, and G# dorian scalse have an F##, which is just a G.
And G# melodic min also has an E#, which is just an F.

 

[trjeam]

A key will have either sharps or flats, not both. Check the key signature and name the notes accordingly.

There are some things to look out for though...

Gbmaj/Ebmin has a B#, which is obviously just a C.
G# harmonic and melodic min, and G# dorian scalse have an F##, which is just a G.
And G# melodic min also has an E#, which is just an F.

what you're talking about is called enharmonics. One pitch, different names..

To the orignal post just check the key signature and it will tell what flats and sharps go in the scale.

*Edit*

I just wrote something that might help you out. You might be getting off because you don't understand the numerical classification behind intervals. Read this and it might help:

https://www.futureproducers.com/forums/showthread.php?p=47199396#post47199396