One Petri dish per hand with universal culture medium (e.g. contact plates, available from laboratory retailers or pharmacies). Permanent marker Adhesive tape Scissors Water Soap

Mark the Petri dish with your name and the date. Divide the Petri dish into two halves, one for the washed finger and one for the unwashed one. This is important so that you can match the two fingerprints later.

Press your unwashed finger gently on the correct half of the culture medium for two to three seconds. Then close the Petri dish again. Now wash your hands well with soap. Repeat the fingerprint on the other half of the culture medium. Close the Petri dish with the lid and stick the edge with the adhesive film (do not open the dish again). Now you have to store the Petri dish in a warm place (not too hot, not in direct sunlight) at least overnight. It may be that you do not see a result the next day; this can take three to four days.

a) Look closely at both sides of the bowl, what can you see? ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ b) Do both sides look the same, or can you see a difference? ________________________________________________________________________________________________________________________________________________________________________________________________________________