Native speaker question on motion verbs

[Donnie Sendelbach]

Dear SEELangers:

I'm in the process of gathering some examples of Russian verbs of 
motion for first-year students for a project.  I'm looking for examples 
of unidirectional motion in progress in the past and future that 
involve neither prefixed verbs of motion nor idiomatic phrases.

Could the native speakers out there please tell me which of the 
following would be better (ignoring the fact that a native speaker 
would likely use "po doroge" instead of either of these two):

Вчера, пока Борис шёл в университет, он увидел своего друга.
Vchera, poka Boris shel v universitet, on uvidel svoego druga.

Вчера, когда Борис шёл в университет, он увидел своего друга.
Vchera, kogda Boris shel v universitet, on uvidel svoego druga.


Would the same choice work for future tense also?  Again, these are 
examples for non-native beginners, so I'm looking for what is 
grammatically correct in demonstrating unidirectional motion in the 
past and future.

Завтра, пока Борис будет идти в университет, он увидит своего друга.
Zavtra, poka Boris budet idti v universitet, on uvidit svoego druga.

Завтра, когда Борис будет идти в университет, он увидит своего друга.
Zavtra, kogda Boris budet idti v universitet, on uvidit svoego druga.


Thank you in advance for your assistance!

ds


Donnie Sendelbach, Ph.D.
Director of Humanities Computing/Lecturer in Russian
Lawrence University
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