Common, yes. Normal, no — and it is the most expensive attrition there is, because you already paid to recruit those families.

Fifth to sixth and eighth to ninth are the points where schools quietly hand students off to someone else, usually because nobody ever sold the next division to the families already inside the building. The fix is unglamorous, and it works: treat your own fifth and sixth graders like external prospects. Introduce them to the middle school faculty. Give them traditions to look forward to. Pair them with older students. Put the same effort into your family as you would into a family touring for the first time.

At one school we worked with, retaining sixth- and seventh-graders was the second-highest priority in the entire plan — ahead of every recruitment strategy on the list.