Work in Progress: Basic Mechanics - does learning by teaching improve the retention of understanding of key concepts?

For two years the dynamics part of a basic mechanics course has been delivered using a "teach back" technique where students worked in small groups, learnt given topics and then taught these topics to other groups of students. The statics part of the course was taught more traditionally using lectures and tutorials. Most of the students enjoyed the method of learning used for dynamics and it particularly increased the motivation of young males (aged 21 or less) who showed a significant improvement in the exam scores for dynamics over those of statics. One class of students, who completed the course 2 years ago, have now been asked if they would be willing to participate in a follow up study to test the null hypothesis: "the retention of understanding of a topic or concept in mechanics is not improved by teaching it to someone else". This paper presents some of the initial findings of this study