For this purpose, 100 nine graders from more than 10 countries in an
independent preparatory school in Doha / Qatar were divided into four
classes and distributed over the following learning “STAD” groups:
a- Heterogeneous by ability but homogeneous by nationality.
b- Heterogeneous by nationality but homogeneous by ability.
c- Entirely heterogeneous (i.e. by both the ability and the nationality).
d- Entirely homogeneous (i.e. by both the ability and the nationality).