In the past, the fens were often a very dangerous place to be. The land was marshy and unpredictable. Fen dwellers used to carry Safe Keeps with them at all times. These would protect them from the bogarts, bogles and any other super natural beings they believed they might come across on their journeys. The children imagined that they were fen dwellers and in the forest found natural items that they thought precious and collected them in their own Safe Keep.
They also investigated artefacts from Ely Museum's Fen box and discussed what they thought these items could be used for.