Abstract
The insufficient capabilities of high school students in Historical thinking skills (HTS) and Higher order thinking skills (HOTS) present a significant issue, primarily attributed to traditional teaching methods that prioritize memorization over critical analysis, particularly in history education. Consequently, this study aims to evaluate how well digital teaching materials that use Inquiry-Based Learning by Primary Sources (IbLPS) can improve high school students' Historical thinking skills (HTS) and Higher order thinking skills (HOTS). A quasi-experimental research design featuring pre-tests and post-tests was employed, involving 300 students from six high schools in Surakarta, Indonesia, selected through stratified random sampling. Data were collected using validated instruments for HTS and HOTS, with analysis conducted via multiple linear regression. The analyzed data show that students' thinking skills improved significantly, with 72% of the differences in HOTS explained by how often they used primary sources, participated in discussions, and used digital teaching materials. The study concludes that the integration of digital resources with an inquiry-based approach substantially enhances students' critical and historical thinking abilities. It is expected that using primary sources in digital learning will encourage students to think more deeply and critically about history, making it important to include this approach in history teaching programs.

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