Abstract
This research examined teaching and learning strategies for GCE Advanced level standard genetics. A diagnostic test was developed and tried that allowed student concepts to be identified. This test was used both before and after any genetics instruction to ascertain what, if any, changes had taken place. This test identified a particular misconception held by many students. This misconception concerned the relationship between the terms Gene and Allele. This misconception caused major problems with many of the other terms used in genetics and thus adversely affected the students' performance in this subject. In order to help the students to resolve this misconception a Chromosome Model was designed that could be used to encourage conceptual change. The findings of this research are that it is important for teachers to be aware of their students' concepts in genetics before they start teaching them the genetics component of any syllabus. It also showed that once the student had resolved any difficulty with the relationship between Gene and Allele their performance in genetics showed a significant improvement. This research found that the use of the Chromosome Model as a conceptual challenge tool was a most effective way of resolving the students' difficulties with the relationship between Gene and Allele and, consequently, other aspects of genetics, especially if their teachers were aware of their students' concepts, and had undergone some staff development in the Model's use.