Some days, we bring all of the students together into one large classroom, and I teach the main math lesson to groups of students while she teaches smaller groups of students in guided practice. I teach all of the students and because there are two adults we can have students switch groups immediately if that is needed.
In reading, she takes some of my students who need additional assistance, since that is her area of expertise for over 20 years. She also helps me plan out my lessons and novels. Working together we are much better teachers than we would be on our own.
Last year I sent students to different teachers for both math and reading, depending on the grade level and skill of each student. Some times it felt like I didn't have much time with my second grade students (the ones who did the most moving.) If I only worked with them that one year, the connections and relatinoships wouldn't be as deep as they normally are in elementary school.
But, I have looped with my younger students. While they might not be with me for the whole day, I have gotten to know these children well over the course of 2 years. By specializing and looping I am developing a strong relationship with each child and their families, as well as giving them a strong academic situation. I think this is a win/win situation!