The Major Pentatonic Scale

The major pentatonic scale is probably the best place to start improvising.
This scale has only five notes but there is a lot that you can do with these five notes.

What is the major pentatonic scale?

If you take the major (Ionian) scale - a seven note scale - and drop the 4th and the 7th, you
have a major pentatonic scale. 

The five black keys on the piano form a major pentatonic (Gb) scale.  As you will observe, the
missing 4th and 7th are the white keys on either side of the 3 black keys.

              Modal Improvisation - Gb Major Pentatonic

The C major pentatonic scale is all white keys. The missing 4th and 7th are also the
white keys on either side of the 3 black keys.

 Modal Improvisation - C Major Pentatonic

I give you two pentatonic scales. Now you form the rest by applying the principle
outlined above.