Have a special situation with one of my students. He started flying in 1992 and got up to solo in a Piper Cub. Has 2 hours of solo in the pattern. I've gotten him back up tp speed in a 172. Do I endorse the students old Student pilot certificate for the new airplane of have him get a new Student pilot cert/Medical ? ? I remember a examiner mentioning something about this during the CFI oral which made it sound as though I should endorse the old one. Thanks for the help guys/gals