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Based on an exploratory study carried out recently, and observations from several sessions of university teaching-learning in Morocco, we have found that the difficulties encountered by Moroccan teachers in scientific disciplines are mainly due to the problem of massification. This observation led us thereafter, to design a collaborative method of problem solving by algorithms, to bring more efficiency to teaching practices in graduate studies. Indeed, by forming a small groups of students, the teacher establishes an algorithm which he will follow during a whole activity, proposes to each group problems of variable complexity, then, he returns each time to the progress of this algorithm, in order to observe the progress of the work entrusted to the students groups. After integrating the method, observation grids and results from questionnaires, intended for an example of 70 students of the second year of Chemistry of Materials Science, at the Ben M’sik Faculty of Sciences in Casablanca, showed that the subjects are motivated by the method, and that the work within the group helped them to improve their learning. On the teacher’s side, the choice of method has positively influenced these practices, particularly for the management of time and space in his teaching.

Methods of chemical preparation and crystallographic data are reported for two new condensed phosphates: a polyphosphate of nickel and cesium, NiCs4(PO3)6, and a cyclotriphosphate of nickel and potassium, NiK4(P3O9)2. NiCs4(PO3)6 is rhombohedral with the following unit-cell dimensions: a=b=11.602(1) Å, c=9.078(1) Å, space group P−31c, V=1058.24(1) Å3, and Z=2. NiK4(P3O9)2 is triclinic with the following unit-cell dimensions: a=6.143(8) Å, b=6.80(1) Å, c=12.80(3) Å, α=102.8(3)°, β=89.7(2)°, γ=66.03(7)°, space group P−1, V=473.56(3) Å3, and Z=1.

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