We propose an experimental activity in order to develop a mathematical model that relates step length and walking speed of human beings. We employ two well-known physics teaching softwares, namely, Tracker to carry out the video analysis and LibreOffice/Calc to obtain graphs, trend lines and equations. The predictions of our model are compared with those of similar models present in the literature. This activity is simple, practical and viable in the most diverse school circumstances, and it has been applied on several occasions in high school lectures at our institute. We have found that it can be, in many ways, useful in physics teaching.