TY - JOUR T1 - Přímá a nepřímá úměrnost (nekorektní stať o kritickém myšlení) A1 - Bečvář, Jindřich JA - Obzory matematiky, fyziky a informatiky Y1 - 2020 VL - 49 IS - 2 SP - 11 EP - 22 SN - 1335-4981 N2 - The article is devoted to several types of problems from school mathematics. It shows possible uses of the rule of three, direct proportion, and indirect proportion. Some pitfalls that need to be avoided are demonstrated on several examples. ER -