A PST problem is an interactive situation in which a student has to assume his or her responsibility in gathering, assimilating and exchanging new information in a group. It is structured so that it presents the student a "puzzle"; it cannot be solved readily by the activation of a student's previous knowledge.

PST Summary.

First two weeks -
-Each team of 3 students identifies and distributes among its members the different parameters and the laboratory procedures elaborated to solve the problem.
-Each student experiments one of the 3 different pilot procedures elaborated by his team and exchanges results with team mates. Each team chooses a procedure .

Third week
-During this exam period each student experiments the procedure chosen, or synthesize a compound imposed by the professor.

Fourth week
-Students write their report in the lab, under "examination" conditions.
-The teacher corrects each report with a correction chart .

End of the semester
-A survey of the P.S.T. pedagogy is made in each group and is analysed with each class president.

Conclusion:
PST pedagogy develops students' scientific initiatives, creativity, responsibility and communication abilities.