As an English activity for Letterwriting, I had my Year 3 children to compose letters to Father Christmas. They personalised them with information about themselves and also, importantly, asked questions. (We had a discussion session first to decide what sort of questions they really wanted some answers to, we tried to think of unusual ones, not silly).

They decorated them and put their name age etc on it. We "sent" them via the school letter box. A colleague had her Yr 6 children reply to them!

Each chose one child to reply to and assumed the identity of the person (Father Christmas, an elf etc) the Yr 3 child had written to. The Yr 3 children were staggered to have received a "genuine" reply and of course it appeared so because each question had been answered!