Hair can incorporate drugs through the blood and remain in hair until cut off, showing historic drug use. A case study found 73% of hair samples from children living in meth labs tested positive for methamphetamine. Lecturer credibility is defined as being trustworthy and believed. A presentation discussed using research and experience in teaching, theories on the relationship between teaching and research, and research conducted with students on their views of lecturer credibility and the use of personal experience in teaching. Students generally felt experience enhanced learning when relevant and was important for credibility but theory was also crucial.