[General] in?/on a plane (commercial airlines)

[sitifan]

https://www.youtube.com/watch?v=sN5H7YTo_IQ
According to the above link, people say "in a taxi/car, " but "on a train/bus/plane."

But according to the link below, "in a plane (commercial airlines)" is also correct.
https://www.usingenglish.com/forum/threads/283445-I-ve-never-been-on-up-in-a-plane

Which should I teach my students?

 

[jutfrank]

Teach them on a plane. The phrase in the second link is up in a plane, which has a different use.

If you tell us more about your students, we'll be able to give you better advice. How old are they? What's their level?

 

[sitifan]

How old are they? What's their level?

They are 14 years old. Their English vocabulary is about 1000 words.