She's done it again!

I get on really well with Ajarn Rattana, her English is the best in the department, and generally she's really nice (and she's the only teacher who gave me any indication of what she wanted me to teach). But the last two weeks she keeps taking over my periods. I wouldn't mind in the least (except that I quite like my M6 classes), but she doesn't give me any warning! It doesn't help that I'm totally confused anyway because the exam timetable keeps changing: first the end-of-year exams started on the 14th, then it was only M6 exams from the 14th and we'd have classes with the other Matayoms, and Karina told me yesterday that the whole thing has been shifted back a week, so I asked Rattana this morning if Matayom 6 had classes this week. "Of course," she said. So I spent the next half-hour scrambling to prepare something! I had a spare lesson plan, but there's no time to get photocopying done before the class, so I'm printing out 25 copies of the two-sided worksheet – in bright pink, the only colour ink remaining in the printer, which takes ages. I rush to class, five minutes late, to find Rattana teaching my students! "Do I teach this period or do you?" I ask her. "Oh, can I have this period?" Well sure, but you might've told me when I asked earlier. Mai pen rai – at least I get a free period out of it.