In this work, we present a proposal of chemistry teaching that was developed to enable the active and autonomous participation of the student, as well as to improve their processes of concept construction and development of skills and abilities. The work was developed in the laboratory based on the perspective of Learning by Research, which was generated from an experimental problem of stoichiometry around a research process. The problem to be solved was the determination of the amount of Sodium Bicarbonate (NaHCO3) in an Alka-seltzer® sample by two different methods; the method for mass loss and the method for gas collection, after that, students must to validate results from repetition, determine the precision and accuracy of the results, using parameters to analyze the values obtained.