Nowadays many of us know that in an introductory statistics course great emphasis should be placed on problem-solving and active learning. This paper presents a real capture-recapture experiment used as a starting point to introduce fundamental concepts as experiment, sample variation, sampling distribution and bootstrap. It has been used in an introduction to statistics 2 course for undergraduate biology students; a particular attention has been given to their special interest in learning how to use statistics to solve problems and to their general negative attitude towards this discipline. A bootstrap application, based on the observed experimental data, has been carried out using the R package. Student feedback and reactions are also discussed.