High school students’ difficulties in understanding osmosis

Preconceptions and misconceptions of 500 secondary students in years 9‐12 regarding osmosis were studied through the use of five different kinds of instruments: prior learning inventory, self‐report knowledge inventory, true/false test, definitions and clinical interviews. Some of the major findings were: (1) The most frequent explanation offered to osmosis is ‘a desire or drive towards equalizing concentrations’. (2) Hardly any student uses the concept ‘water concentration’. (3) Most students fail to realize that in dynamic equilibrium water molecules keep moving. (4) Students have special difficulty in understanding osmotic relations in plants. (5) Many students have difficulty in grasping solute‐solvent and concentration‐quantity relations. (6) Students often perform laboratory experiments without really understanding the underlying principles. Practical and theoretical implications are discussed.