I had a very able top set last year, and what I found they liked best was to write about and discuss more sophisticated topics and themes for their controlled assessments. If they,re able in MFL, then chances are they are good at a wide range of subjects, and these kids often find writing about their bedrooms or their pets a little mundane. My group really enjoyed preparing for a piece of writing for example in which they discussed environmental issues such as nuclear energy and solar panels and discussing teenage smoking and drug taking. It all involves the same structures, but makes them feel like their MFL lessons are as relevant as everything else they are studying. Hope this helps.