Instead of learning the different modes based on their relationship to their RELATIVE major scale, learn them based on their PARALLEL major scale. RELATIVE scales have the same notes but a different root. Think about the relative relationship between Bb major and its relative minor scale, G Aeolian (or natural minor). PARALLEL scales have the same root, but different notes. Beginning on the same root makes the scale experience immediately familiar, and makes the "new" scale only slightly different from the familiar one.
To return to our C Dorian example, the notes of C Dorian are: C - D - Eb - F - G - A - Bb. This is the same a C major scale, except for the Eb (lowered 3rd) and Bb (lowered seventh). Thinking of a dorian scale as a major scale with a lowered third and lowered seventh allows students to take something they already understand - a major scale -- and make only slight changes to it to create something new.
The end result, of course, is the same. I think this route -- learning the jazz scales based on how they compare to their parallel major scales -- is an easier way to go. Below is a table of how to realize all of the modes based on their parallel major scales.
MODE CHANGES TO PARALLEL MAJOR SCALE:
*Dorian b3, b7
Phrygian b2, b3, b6, b7 (not as common)
Aeolian b3, b6, b7 (also called natural minor)
Locrian b2, b3, b5, b6, b7 (not as common)
Of the scales above, the most commonly used BY FAR are those marked with asterisks (Dorian and Mixolydian). Lydian and Aeolian are the next most common, while Phrygian and Locrian are used less often. Try thinking of these scales in relation to their parallel major scale. I think you will find them much easier to learn and play. Happy Practicing!