My son, 9, has the option to take math next fall at the upper elementary school, a different school, where he would be placed in the most advanced fifth grade math class. He would be the only student in fourth grade at his current school to do this. Alternatively, he can stay at his current school, and be clustered with a group of 4 or so other rising fourth graders who are similarly advanced in math. His fourth grade teacher would cover the established curriculum for medium-advanced fifth grade math students. In previous years students have gone to the upper elementary for math, but this is the first time they have tried clustering and teaching these advanced students "in house". We seem to be the only family that's been given a choice of the two options. The school has been terrifically helpful, and both options seem great, but I don't have a good sense of what questions to ask , or criteria to weigh in order to decide between them. Any advice, experience?