Children are rostered on to take home the Mystery Bag.  

The bag is taken home with a note to the parents explaining that children need to bring in a mystery object chosen from home for the next day.

Children are also to come up with some clues about their object with the help of their parents.

A framework for organising descriptions (see below) could also be sent home to be utilized formally by actually writing clues down, or for younger children, as a guide for discussing the clues.

Back at school, draw up a large version of this framework on the board, or chart and fill it in as the whole class sorts through the clues provided by the 'mystery bag' holder.  

This framework is also great for guiding questions about the object from the class.