The activities that we present consist in determining the values of the parameters of a real variable function. These parameters are determined so the function visually adjusts to a set of experimental data or so that it satisfies certain conditions. For this we propose a function whose parameters are expressed as GeoGebra sliders. We change the parameters looking for the function that better describes the situation. From the didactic point of view, the purpose is to develop in the students capabilities related to the analysis of the role of each parameter in the mathematical model and to compare different models with each other. In particular, as a novel use, we point out that we have used these procedures in the framework of scientific research to determine parameter values of growth models. These values were used as the initial values to accelerate the convergence of linear or non-linear approximation methods with other tools. This work is illustrated with didactic-oriented examples and growth models used in forestry engineering.