When they started kindergarten we asked them for their opinion; did they want to be in the same class? Mary was certain, same class, but Kate wavered. On the first day of school it was Kate who clung to Mary as they walked in together, to the same class, a decision we all made together, based in part on the simple fact that they had never before been to school. It didn't seem that their initial classroom experience should be the first thing to separate them after five years of togetherness.
The next year they were apart, Kate moving into a split grade class. Mary was nervous initially but they did well and were often so happy to see each other at the end of the day the incessant bickering was slowed, thanks to the seven hour break from one another.
Reunited for second grade, and now third, they have done well spending every waking moment together. They save the bickering for me, they help one another in class and have successfully shared lunch items. Their unique strengths have benefited the other: Mary pulling Kate into the social circle of third grade and Kate pacing Mary to a more focused study time. It's not perfect but for two years this arrangement has worked well.
Recently Kate has started to muse about going to another school, one that would be, perhaps, more suited to her strengths. It's not going to happen next year but she is curious and we've agreed to explore the possibility. Last night at dinner the separate school question was raised, the first Mary had heard of this idea.
Before Kate finished her thought Mary was crying, "no Mom, no. If Kate wasn't there the classroom would feel empty".
A classroom of 19 children would feel empty to Mary if her sister wasn't at the next table; the conversation just became much more complicated.