This study aims to examine students' reasoning based on the model in each laboratory work style and find the effect on scientific attitude and student activity. This study uses a quantitative approach with the experimental method. The study was conducted in three classes with different lab work styles. Arduino and sensors were used as a measurement apparatus in Ohm's law experiments that will stimulate students' reasoning in each lab work. The measuring instruments consist of a scientific attitude scale, observation sheet, and worksheet. A descriptive statistical analysis was used to describe students' reasoning in the three laboratory work styles. The improvement of scientific attitude and activities were analyzed by normalized gain. The effects of the three types of lab work to scientific attitudes were analyzed by analysis of variance (ANOVA). The results show that the style of lab work gives rise to various students' reasoning. Observations show that many students solve problems in the experiment by reasoning to improve the measurement model. Problem-solving laboratory work is effective to improve activities and scientific attitudes. This study has succeeded to discover alternative concepts in the laboratory work with reasoning based on models.