@ARTICLE {, title = {Čo všetko nám prezradí jednoduchá úloha}, author = {Kupková, Erika}, journal = {Obzory matematiky, fyziky a informatiky}, year = {2000}, volume = {29}, number = {3}, pages = {14--19}, issn = {1335-4981}, abstract = {12-years old children are given three or four different answers to the same mathematical problem. They have to decide which of them are right and why. Their strategies of result checking are studied and analyzed.}, }