For the reasons mentioned above, we chose to teach
atomic structure using a modified jigsaw-classroom method
(20). This jigsaw classroom design contains three subtopics
for expert group work. Each of them is assigned to two different
expert groups. The students work on the subtopics using
given materials: (i) Rutherford’s experiment and the
nucleus-shell-structure, (ii) structure of the atomic nucleus,
and (iii) structure of the atomic shell. An overview of the
activities is given in Figure 1. Working out these contents in
the expert groups using the lesson materials provided (37)
takes about two lesson periods (45 minutes each). Expert
group size consists of five students (30 total). The learning group
phase also takes up about two lesson periods. The learning
groups are made up of six students each. A fifth lesson
period is used to compare the results, for discussion and feedback,
and for filling out the evaluative questionnaire. It is
recommended that a written test be administered after the
jigsaw-classroom lessons have been completed.