I like to begin students by teaching them one-octave scales.
What is a One-Octave Scale?
A one-octave scale just means a scale spanning the range of one octave. (See octaves.)
For example, a one-octave C major scale is:
C, D, E, F, G, A, B, and C from one C to the next C an octave above.
Why Start with Only One-Octave?
Firstly, I like to do this because one-octave scales are easy to play and memorize and are very usable right away. But, I also like to do this because it gives you a good sense of the scale’s structure the notes in the scale and the intervals used to build it.
One-octave scales also fit in with how I teach scales covering the entire fretboard. The better you know the one-octave scale patterns, the easier learning the scale all over the neck will be.
Scales Can Be Played Beyond One Octave?
Absolutely. Scales can be played across as many octaves as the range of your instrument allows. Playing two-octave and three-octave scales on bass is common to practice, too.
A two-octave C major scale would be:
C, D, E, F, G, A, B, C, D, E, F, G, A, B, and C from one C to a C two octaves above.
Knowing the one-octave scale well will make learning larger scale patterns easier.
Remember that scales are just a set of notes. If the note "B" is in a particular scale's set of notes, then any note "B" on your bass is in that scale.