The major scale is often broken up into different modes (scales) beginning on each individual note of the scale. Using modes to play over chord progressions means finding the best group of notes to play over each particular chord.
There are seven different notes in a major scale and each of these notes can be used as the starting note for a different mode. Modes will be explained in detail in lesson 37. Here is an exercise to help you become familiar with the positions of all of the notes within the open position fingering of the C major scale. These are the starting notes for the seven modes, so it is important to be able to find them all instantly.
Once you are comfortable finding all the notes individually, practice playing all the notes in between them from one octave to the next as shown in the following example. Once you can do them ascending, practice them descending as well.
Here is a solo which uses all of the natural notes contained in the various modes derived from the C major scale in the open position. It is played over a chord progression which fits all seven of the modes. Try this approach any time you are soloing over a progression in a major key or one which alternates between a major key and its relative minor. Minor keys and relative keys are the subject of lesson 26.