We all know how important interval identification is in understanding the basic building blocks of harmony. 

Here is a great website to test your knowledge and practice! 

https://www.musictheory.net/exercises/interval

 

Remember that while maintaining the integrity of their interval # (1-8) the qualities will change when:

*Major intervals become a half step closer in pitch= Major becomes Minor (-)

*Perfect intervals become a half step closer in pitch= Perfect becomes Diminished (°) and can be a double 

*Perfect and Major intervals become a half step wider in pitch= Major/Perfect becomes Augmented (+) and can be a double

* A double occurs when Perfect/Major intervals become two half steps closer or two half steps wider in pitch

:)