A case of the lower secondary science teacher training course for improving knowledge about classification of igneous rocks

In Japan, lower secondary school students study classification of igneous rocks related to geomorphology of volcanoes in science classes.
Most of junior high school science teachers are not good at teaching about this field. It might be due to their poor study experiences in earth science. They studied basic geology only in elementary and lower secondary school science classes because upper secondary school science curriculum have not been covered all fields of science. Consequently, many science teachers prefer to show photographs of rock samples to their students and are apt to avoid instruction of observing rock for identification. This may cause disadvantage for their students to construct the knowledge about plutonism and volcanism. 
To improve instructional methods of basic petrology of igneous rocks, one of us conducted teacher training courses for lower secondary school science teachers. The results and subjects are as follows;
Firstly, an instructor showed three volcanic rocks (rhyolite, andesite, basalt) and three plutonic rocks (granite, diorite, and gabbro) to the trainees with no label. The trainees tried to classify the samples into some groups based on any points of views and present the results to others. Through this activity, the trainees would be aware of many points to divide igneous rock into some groups.
Secondly, the trainees observed and divided the igneous rocks into two groups on the basis of those textures. After the grouping, the trainees found the differences of colors among the rocks, and arranged in order from the white one in each group.
Thirdly, the trainees identified these rocks by utilizing a rock chart and references. 
Finally, an instructor talked to the school teachers about relations between diversity and chemical components of magma. 
According to a post questionnaires survey, some teachers replied as follows, "I knew the difference between the stones." "I did not know the points, now I knew it." " I had gained more confidence in instruction." “I feel that I have improved my teaching skills about this field.” In short, some trainees could improve their knowledge of basic petrology and instructional skills. 
It is necessary to conduct training for teachers in order to prevent disadvantages to the students based on the teachers' experiences . 
 I think it is necessary to increase the number of teachers who improve instructional methods of earth science (experimental observation) by conducting training to improve the skills of many teachers.