In our current study, we combined both approaches and designed a teaching‐unit consisting of hands‐on as well as computer‐based learning. Because of the ambiguity of the genetic concepts, we focused under specification of the hierarchical organizational level on the tendency to maintain alternative conceptions. Our main objectives were (i) to develop a questionnaire using the ‘draw and write’ technique to measure students' conceptions of the DNA structure within a given hierarchical organizational level, (ii) to design a computer‐based learning unit in combination with hands‐on activities in an outreach laboratory on the topic of DNA which concentrates on the organizational levels to improve conceptions, and (iii) to create and implement a category system for evaluating the results.