I have a few questions about this...
At music theory we were listening to intervals (only minor, major second and minor, major third) and I had really a lot of mistakes

And I don't have problems with dictations anymore so I don't understand how can I hear all the notes in the dictation right but I can't hear the interval between just two notes right
We were listening to 26 intervals and I had ...

10 mistakes!!!

So it was really bad! (even though I would have only 8 mistakes cause I changed what I wrote first but didn't change it completely so the teacher counted the first thing I wrote).
But well yesterday when I was looking at the notes and intervals that we were listening to again, I noticed something weird. Out of all 10 mistakes that I had, 5 of the intervals that I got wrong started on the same note, and one more ended on that note and that was the note g # (or a flat). Can that be just a coincidence? Or do I have problem hearing the intervals with that note?

Or could the piano be so out of tune on that note?

(which would be kinda weird right?)
And I also noticed that sometimes I hear the intervals really well, but then sometimes I just get confused and I just think that it's a major third when it's really a minor and the other way around.
Is it ok if I practice this on my keyboard (pressing the keys and looking away) or would it be better to record it and then listen to it... or would it be better to play the intervals on my piano (which is out of tune) to get used to a little out of tune intervals or something?

Well if anyone has any suggestions or anything else that would be great (cause I'm a little confused about all this) !
