Chris explain quite nicely what you want to do and the lesson is a great way to practice. Taking off from what Chris was saying with regarding to being able to 'ehar' the note you're bending to. The below excersize utilizes the A minor pentatonic. Do the following:
1) One the high E (using A minor pentatonic)
2) The high E notes for the blues scaled pentatonic for this would be A (5th fret), B (7th fret) and C (8th fret).
3) A common bend is to bend the 7th fret note (the B note). Often times this is done with the ring finger holding down the note on the 7th fret.
4) The most common bend is a half step bend. This means that you are going to bend the B note up to the C note.
5) Before executing the bend, just simply fret the note of the 8th fret (C note) first to hear where your bend you will execute from the 7th fret should stop. I'd suggest with that 8th fret note three time to get the sound in your head.
6) Now it's time to execute your bend. Having heard that 8th fret note with three strikes, bend the 7th fret note until it sounds like the same note as the 8th fret. I'd suggest mirroring the 'three strike' thing as well when bending the 7th fret bend.
Repeat and repeat. To Chris' point, it's ok to use the tuner to help you see the bend is right but eventually you have to hear it. Using the tuner handicaps you because you aren't hearing yourself bend the proper interval as the bend you make such as like to the next note in the scale interval might be a full step.
This also avoids the tuner differences as you can apply this skill to other tunings (way down the road).