Debating with physics teacher.

[GeeTwo]

The answer will vary depending on how the teacher defines "the same size" and "air resistance". The most likely meaning of "the same size" is "the same shape and volume"; I'll assume that as the intent. Then, the definition of "air resistance" may be defined either in terms of force, in which case the heavier rock will experience slightly more at any given time, as it will move faster; or in terms of acceleration, time to fall a given distance, or other motion-based measure, in which case the lighter rock will be more impacted by the effects of the air.