Just to ramble on a bit the IP is in the UK and today is a school day for most secondary schools there so posting unhappy edits on an early secondary syllabus related topic just before 6 pm local time may indicate that the editor was doing homework and grew sufficiently bored to try out the anyone can edit thing Which is slightly intentional I suppose It s not quite trolling as such by my definition since it s entirely possible they had no expectation anyone would ever see the edit or react to it The welcome with a link to their contributions might have an interesting effect on that possible lack of awareness