A geography teacher is covering Asia in the current unit. The teacher has found that 18 students are proficient in country names, 7 students are proficient in lakes and oceans, 8 students are proficient in major cities, and 12 students are proficient in major rivers. There are 21 students in the class.

The proficiency of 18 students in country names indicates a strong understanding of this geographical aspect. This high level of knowledge suggests that students are more familiar with the names of countries than with other geographical features, thus making it a more accessible topic for them.

With 8 students proficient in major cities, this area shows moderate knowledge among the students, but still does not compare to the proficiency in country names. The number of students who know major cities is also higher than those proficient in lakes and oceans, indicating that cities are relatively well understood.

The proficiency of 12 students in major rivers indicates a fair amount of knowledge in this area, more than in lakes and oceans but less than country names. This suggests that rivers are a significant part of the students' geographical education, contributing to their overall understanding of the region.