Minor Scales

I've learned "minor scales" in the Music class.
I've known this for long, but I didn't know it clearly. I thought minor scale is just only one kind of scale, but there are three of them and each of them is slightly different. So today, when I went to a practice room, I tried to remember the degrees and its steps by using piano. I wanted to play all of the three, but then I found it wasn't so easy, so I tried the first one, natural minor. I still don't remember the natural minor completely but anyway I'll try other two tomorrow or later.
Piano really helps recognizing the sound and the music theory.