Very few students enjoy playing scales at first, but even fewer understand why they have to play them in the first place. Scales will help with speed, agility and stamina although this is not why your piano teacher has you play them. If a teacher really needs you to work on these areas, exercises by Hanon and Czerny will do the trick a lot faster. Scales are the building blocks of music. As you may know, every piece of music is in a particular key and what that really means is that it uses the notes of a particular scale (major or minor). When you know your scales really well, you are less likely to make errors when playing a piece with say, 3 flats. Piano literature contains all kinds of scales, even just small parts of them, and when you know the scales well, these pieces will be a lot less challenging. Another important reason for playing scales is for the correct use of fingers. The fingering used in scales is generally the same fingering used for many pieces and if you find that you need to write in lots of fingering in your pieces, then work on your scales more so that fingering becomes automatic for you. There are many different types of scales, but I feel that the most important are major, harmonic minor, melodic minor as well as major and minor arpeggios. If you know all of these scales well (12 of each) and preferably 4 octaves, then you will be well armed to tackle just about any piece of music.