my teacher said he will just drop from the spot he jumpe up from, not continue moving in the direction of the plane for a while. Is this the same when i drop a object i am holding out of the car window in a moving car?
Your teacher would certainly make a bad bombardier!
(In defense of the teacher, who is not here to make his/her own defense, I have know students to tell me their teacher said such and such, to find later that the teacher asked if such and such were true in an attempt to get the students to think about it.)
Well, if all you are interested in is how long it takes for the jumper to reach the ground, then even with (a separable form of) air resistance it will be irrelevant how fast the plane was moving, and it will take just as long for the jumper to reach the ground as if he had been jumping from a tower at the altitude of the plane. Also, (with no air resistance) the energy of the jumper is divided into a constant kinetic part along the "x" axis, and a constant kinetic/gravitational potential part along the "y" axis. Maybe that's what your teacher meant? I doubt that your teacher would have forgotten Newton's laws, but even so it sounds like he or she does a bad job conveying the subject accurately.