In this paper the problem of pre-service teachers’ approaches in solving tasks in probability distributions is discussed. Statistical data were obtained from 98 Greek pre-service teachers from the Western Macedonia University that formed the experimental group and 132 Greek pre-service teachers from Macedonia University that form the control group, enrolled in two basic statistics courses. The control group participates in teacher-centred teaching environment. The experimental group participates in student-centred teaching environment connected with probability distributions. Results indicate the difficulty of control group in defining the difference between discrete and continuous distributions. In addition the estimation of the Poisson distribution parameter λ troubled the majority of the control group while the experimental group showed higher success rate.