Problem Solving: How can we help students overcome cognitive difficulties

The traditonal approach to teach problem solving usually consists in showing students the solutons of some example-problems and then in asking students to practce individually on solving a certain number of related problems. This approach does not ensure that students learn to solve problems and above all to think about the soluton process in a consistent manner. Topics such as atoms, molecules, and the mole concept are fundamental in chemistry and instructors may think that, for our students, should be easy to learn these concepts and to use them in solving problems, but it is not always so. If teachers do not put emphasis on the logical process during solving problems, students are at risk to become more profcient at applying the formulas rather than to reason. This disappointng result is clear from the outcomes of questonnaires meant to measure the ability to calculate the mass of a sample from the number of atoms and vice versa. A suggeston from the cognitve load theory has proved a useful way to improve students’ skills for this type of problems: the use of worked out examples. The repetton afer two weeks of the Friedel-Maloney test afer the use of worked examples shows that students' skills signifcantly improve. Successful students in all questons jumped from 2 to 64%.