Worksheet/Instructions for Experiments
A filing cabinet is a good place for these. Failing that, a cardboard storage case or suitable box can be used. They can be arranged in a variety of ways depending on the circumstances, e.g. according to the groups of people that would use them or according to topic. In all cases, an indexing system can be used, together with a "key".
Incidentally, if you are keeping ink or spirit stencils that have been used to prepare these worksheets, the stencils should have the same indexing systems.