Dirty Fingers

IGN Biosciences

Science Bridge


The project shows that bacteria are everywhere and that washing hands (or brushing teeth) will reduce the number of bacteria.


Age group:

6 to 12 years

Number of participants:

Class up to 20 pupils


One day introduction and setting up the experiment with the Science Bridge Team.

Next day evaluation of results and discussion with teacher and Science Bridge Team.



The experiment aims at the awareness that bacteria are everywhere and that they can grow rapidly. On the plates from dirty fingers there is usually a multitude of different bacterial colonies in different colors while there is mostly nothing growing on plates from washed fingers. This is an impressive demonstration that hygiene is important. Basic knowledge of bacteria and bacterial growth can be taught in the course.



Nutrient agar is either prepared in household glass jars or by the Science Bridge Team in petri-dishes.

The participants leave a fingerprint on one plate, then carefully wash their hands with lots of soap and then leave a second finger print.

Alternatively, a swap from the teeth can be smeared on the agar plate before and after brushing the teeth.

The plates/jars are incubated overnight and examined the next day.

Importantly, the participants have to be involved in the decontamination process, i.e. boiling the plates/jars after the experiment to kill potentially hazardous bacteria.



For the introduction, a PowerPoint presentation is prepared to explain what bacteria are and that there are good and bad (disease causing) bacteria.

A detailed protocol is established how to prepare the nutrient agar. The practical work is accompanied by a PowerPoint presentation showing in detail how the experiment is done.


After 24 hours of incubation the plates are examined and bacterial colonies are described and compared between different participants. Results may be documented by photographs.



Several schools in Malang will be contacted for pilot experiments and the experiment will be carried out with one class each. In addition, the experiment is prepared as a chapter for a “Kid’s Science Book” in collaboration with Widhi Adrianna.



The experiment can be extended with swaps from different sources like towels, bathroom seats, soil, sewage etc. to provide insights that bacteria are ubiquitous.

We may establish a Facebook site to show and discuss the results from the participants and to provide further information.


Further measures

The project requires minimal financial support that can be provided by the schools.


Dissemination of the project

On this page we will report on further progress in the development of the project.

With successful implementation of the pilot courses we will offer a training course for interested groups of students and lecturers from IGN partner universities.

Teaching materials will be made available to the other IGN partners.


Progress as of Dec. 30th, 2015

Some graphs have been produced by Widhi Adrianna, otherwise the project is in the very beginning.