On May 13,2024, Ms. Vannak Sim led the 7th grade students of American Intercon School, Choam Chao campus, to do experiment on the topic of: Identify oxygen and carbon dioxide. To experiment, students need materials such as beaker glass H₂O₂, MnO₂, Ca(OH)₂, pipes, incense, triggler etc_…. After the experiment, the students notified that the oxygen kept the fire and can ignite incense. On the other hand, carbon dioxide transforms lime water from clear to translucent after oxygenation. After explaining to the students, teacher divided students into groups of 4 or 5 and the students practiced this and got the good result.