The influence of heuristical strategies upon the level of two experimental classes is studied in this paper. The didactic experiment took place at secondary school in Cluj-Napoca, in 2008-2009 school year. The study theme "The Unsaturated Hydrocarbons--Alkenes" has been efficiently learned by using the most active methods: laboratory experiment, brain storming, modeling, problematization. The results obtained in the research demonstrate the efficiency of interactive methods in teaching-learning process.