This study explores how laboratory activity with the argumentative approach could promote
students' conceptual understanding in the Hess' law energy cycle through laboratory work.
Laboratory work with an argument-based inquiry instructional strategy was set up to 15 preuniversity
students from one of the Form 6 Centre at the West Coast Division of Sabah,
Malaysia. The laboratory work consists of a guided inquiry-based instruction with an
argumentative approach in the topic of thermochemistry. The students' understanding of the
energy processes was analyzed with a qualitative method using a semi-structured interview
and triangulated with conversation analysis. The data collected from students' conversation
during the activity was then triangulated with reflective writing at the end of the laboratory
lesson. The study shows the students' prior knowledge and argumentation discourse
significantly influences the development of conceptual understanding. This study emphasizes
argument-based inquiry (ABIIS) in laboratory work to enhance their conceptual knowledge in
the laboratory.