learn the intervals of the major scale then learn the intervals of the minor pentatonic, ur teacher was half right, he was thinking shapes and not theortically or he knows but thought u couldnt handle the knowledge behind it. i know being a teacher myself. lol. you could instead of playing the first pentatonic shape play the second position instead of the first. this will give you the major pentatonic. but not the necessesary understanding as to why they sound different. thats where a bit of trusty music thoery comes into play my lil amigo. (modded tenacious d quote). with the minor pentatonic u have the

1 m3 4 5 flat7.

with the major pentatonic you have the

1 2 3 5 6

so compared to the minor pentatonic you have the root a major 2nd(tone gap) major third (two tone gap) perfect 5th. (3 tones 1 semi tone gap) and a major 6th. (4 tones one semi tone gap) gaps being all fromm the root. this is what makes up a major pentatonic. the main note that changes it from major to minor is the 3rd. the major 3rd to the ear dicatates its happy. and the minor 3rd dicates its sad. once u know where all the major and minor 3rds are from where ever ur root is. ull be able to create a sad or happy vibe.