Originally Posted by Mr and Mrs P
The issue we wanted to have some ideas for is the fact that he would need to switch buildings during a school day.
Sorry, this was not clear in your initial post which seemed to indicate the school was offering only these two options:
- full time placement in building which houses 4th grade (providing 5th grade reading in 4th grade classroom)
- full time placement in building which houses 5th grade (being whole-grade accelerated)

It did not seem that the school was offering an option to spend part of the school day in each building. However I understood your post to indicate that you were somewhat uncomfortable with each of the two options offered by the school for various reasons and were seeking to create additional options, which would include splitting time between both buildings, with possible single subject acceleration in reading. And possible single subject acceleration in math?

Originally Posted by Mr and Mrs P
switch buildings during a school day. Personally, I don't see how it would be such a large issue since the buildings are in close proximity, but that is not what the principal was indicating.
Some possible issues to consider may include: whether the class schedules are aligned/coordinated between the two school buildings, school liability for supervising child throughout the school day (child could not walk alone across football field), amount of time required to walk from school to school during pass time between classes may cause student to be routinely tardy. You may wish to ask the principal directly what his specific concerns are for the logistics.

Originally Posted by Mr and Mrs P
The principal's idea last fall was to keep DS in the elementary building and just give him fifth grade reading curriculum in a fourth grade classroom, I have grave doubts he will get the instruction he needs / deserves because teachers do not have the time to spend with one child on a different curriculum than the other 25 students. It's not fair to DS or to the other kids.
Because "giving him fifth grade reading curriculum in a fourth grade classroom" is somewhat nebulous, did the principal specify that the classroom teacher would be instructing your child? And/or is the curriculum an online curriculum? And/or would a teacher aide be involved? And/or would the child receive curriculum and be expected to be largely auto-didactic? Would there be any other children also receiving this 5th grade reading curriculum in the fourth grade classroom? You may wish to learn more about what this option entails, prior to making a decision.

Originally Posted by Mr and Mrs P
switch buildings during the day and could share how their school handled it
usually by school bus however schools were a greater distance apart