The school is split 50-50 Spanish/English and many subjects (e.g. Math) are taught in both.

Advantage of being in 1st grade all day? More academic, simpler, might make it logistically easier to implement the other accommodations we think he'll need.

Here's another complication: we will be on leave the second half of the school year and DS will probably go to a regular English language 1st grade for that time. This makes planning for year 2 in the dual immersion setting difficult.