This paper addresses the importance of evaluating evidence for enriching critical thinking in the chemistry classroom. The purpose of the study was to examine the usefulness of a historical chemical controversy in promoting students' assessment of evidence. The investigation was conducted in a high school in Melun, France. 63 participants (24 females and 39 males aged 16-17 years) evaluated evidence relating to the polemical question of who discovered oxygen, with Carl Wilhelm Scheele (1742-1786), Joseph Priestley (1733-1804), and Antoine Laurent de Lavoisier (1743-1794) being possible contenders. This evidence was provided by the play "Oxygen", written by Carl Djerassi and Nobel laureate Roald Hoffmann (2001a), and was classified as either experimentation in science or scientific communication. The findings indicate that this historical chemical controversy helped to raise the students' awareness of the essential role of evidence evaluation in the advancement of chemistry. Furthermore, they reveal that the participants evaluated "easier" evidence relating to experimentation in science rather than evidence relating to scientific communication. The main conclusion drawn from this study is that historical chemical controversies can enhance learners' assessment of evidence.