That, alas, would result in an effective 5,000 foot descent at speed. Which result in a pile of red mush on the classroom floor.
However! Assuming that teleporting an object requires energy (and we live in a well-ordered universe, so OF COURSE it does) that kinetic energy could have been paid back to the 10,000 foot displacement.
Mechanics of the energy transfer are left as an exercise for the student. 👨‍🎓