Every piece of material put in a common incubator or other common equipment has to be identifiable. Therefore mark all material with:

• Your name or Initials
• Lab (for example LGM)
• Date
• What it is (for example E. coli or plasmid name and medium)

If you have a collection of small tubes, write on a piece of tape or paper and attach it to the tubes. All material has to be dated. There also has to be an entry in your lab manual to state what was done, at least a reference to a protocol with potential deviations from the standard procedure.