Experiences

Osmosis

Chiara Cheti

Italy

Vocational School

Chemistry, Biology

Teaching in class, Laboratory, Online Learning

Direct

Teaching of scientific subjects often crashes with objective difficulties of the students who do not understand how these disciplines explain real-life events and/or situations. Moreover, the indispensable use of mathematical formulas and scientific laws misleads students to learn by memorizing rather than by understanding.
During our didactic activity, we have organised in cooperation with the students some laboratorial courses integrated with ICT tools (research on the Internet to identify didactical path). This kind of activities lead the students to extrapolate the law, the formula or the graph from the practice into the laboratory. The students were very interested in this methodology because they had the possibility to build their own knowledge. For instance, the osmosis is a key concept for the study physiology of the cell, but hard to understand. Through the above mentioned experience the students understood the relevance of the water movements between the cell and the extra-cell space (Biology). They have also deepened their knowledge about the homogeneous solutions, the mixtures (homogeneous and heterogeneous) and about the different methods for separating out them (Chemistry).
The activity is very simple to be replicated; it is necessary to have common material like a potato, water and sugar. By halving the potato and digging a bit one half we can demonstrate the phenomenon of osmosis putting some sugar into the cavity created and placing the potato into a container with some water (without cover the border of the potato). After very few time it can observe the dilution of the sugar within the cavity because of the water is entered the potato due to the different concentration (osmosis). The experiment works also in reverse order.
Students have appreciated this didactic approach with much positive results also for their study motivation and for the improving of the awareness of their own potentialities. The use of the ICT has, moreover, enlarged the knowledge of the students of the first two years in preparation for the professionalising three following years.