DD2's teacher thinks she should skip top primary and start secondary in Sept. It's quite common here (France), but we're v unsure about it. She is tall for her age so wouldn't look physically out of place, but she is one of the youngest in the year, still quite little-girly and nothing like as emotionally mature as DD1 who started secondary this year.
Still, teacher fears she'll be understimulated at primary and we don't want her to get into the habit of coasting through school (which she is at the moment, though she denies being bored).
Plus there's the issue of DD1 who might feel threatened by her little sister "catching up" with her.
Is it be a terrible idea?