This study explores the role of task design in promoting variational thinking through the PyLVar principles in mathematics education, with a focus on incorporating technological and scientific tools to enhance modelling and argumentation skills among high school students. Interactive mathematical tasks based on the PyLVar principles were developed and implemented, integrating data science and STEAM tools. A qualitative - descriptive approach was used to design, implement, and analyse these tasks, which centred on variational thinking, argumentation, and modelling. The sample consisted of nine 11th -grade students from a public school, selected for convenience. Data were collected through experimental activities, processed with technological tools, and analysed using variational strategies. The students showed significant improvement in their mathematical modelling and argumentation abilities. The tasks, grounded in PyLVar principles, facilitated the identification of variation patterns and promoted critical and analytical thinking. Contextualized interactive tasks not only enhanced variational thinking but also prepared students to solve real-world problems by linking abstract concepts to practical applications, while fostering the integration of technological tools and interdisciplinary approaches.