That optional instruction takes an hour out of instructional time for all the students. I do not know of any teacher who would continue regular instruction (math, reading, science, etc.) with a portion of their students (even a small portion) out of the classroom. When I have students out of my room for additional services (reading, speech, social services, etc.), I read to my kids or they have a work period, when they can work on previously given assignments. I would not consider introducing new material, or giving any kind of lesson.
BULLSHIT!
From both sides of the coin, as a teacher and a parent, I call bullshit on this! As a teacher, no way could you stop instruction when a samll group is out of the classroom. Nothing would ever get done! Been there, done that....you just keep going and help the kid catch up when they get back (most of the time, anyway...sometimes the child is not responsible for what was missed).
And as a paretn of a 3rd grader who is pulled out for an hour, three times a week, (for the "gifted enrichment" program), he is still responsible for what was done in class while he was gone. He misses either 3 social studies or 3 science classes each week (the switch), and he still needs to know all the info for the tests.