International Journal of Evaluation and Research in Education (IJERE) Vol. 13, No. 1, February 2024, pp. 503~510 ISSN: 2252-8822, DOI: 10.11591/ijere.v13i1.25470  503 Journal homepage: http://ijere.iaescore.com Development of Android-based virtual laboratory media at vocational school: effects on students’ cognitive skills Aisyah Khilawatun Niswah, Roemintoyo, Triana Rejekiningsih Department of Educational Technology, Sebelas Maret University, Surakarta, Indonesia Article Info ABSTRACT Article history: Received Dec 31, 2022 Revised Sep 2, 2023 Accepted Sep 20, 2023 Vocational school students are not only required to master competency skills but also cognitive skills. Engineering mechanics learning is a basic calculation lesson that students should master. This research aimed to develop and identify the effectiveness of Android-based virtual laboratory (V-lab) media to improve students’ cognitive skills in learning engineering mechanics at vocational school in Surakarta. The subjects comprised 70 students of first grade vocational school majoring in civil engineering in Surakarta. This research was a research and development (R&D) study to develop an Android-based virtual laboratory media. Testing the N-Gain analysis in the experimental and control classes was to determine the effectiveness of virtual laboratory media in improving students’ cognitive thinking skills. Data were obtained from questionnaires and pretest and post- test test sheets. The developed virtual laboratory media was considered ‘very appropriate’ by media, material, and practitioner experts. The average value of N-Gain for the experimental class was 78.19% which was included in the effective category. Meanwhile, in the control class, the average N-Gain value reached 54.07%, which was included in the less effective category. This indicates that the use of Android-based virtual laboratory media for learning is more effective than conventional learning media. Keywords: Android-based media Cognitive skills Engineering mechanics Virtual laboratory Vocational school This is an open access article under the CC BY-SA license. Corresponding Author: Aisyah Khilawatun Niswah Department of Educational Technology, Sebelas Maret University Jalan Ir. Sutami No.36, Kentingan, Jebres, Surakarta, Central Java, Indonesia Email: aisyahkhila6@student.uns.ac.id 1. INTRODUCTION Vocational secondary education is education at the secondary level that prioritizes the development of students' abilities to carry out certain types of work [1]. Vocational high school aims to prepare students to enter the world of work so that the absorption of graduates, the waiting period, and the first salary become the indicators of effectiveness [2]. Besides prioritizing competency skills, students are required to master cognitive skills. Previous research examined the effects of vocational high school outcomes on the world of work and revealed that students who possess vocational skills and knowledge have a positive effect and better integration into the labor market [3]. Another research also found that cognitive competence affects students' performance when they enter the world of work [4]. Vocational schools equip students with knowledge and skills in various subjects in accordance with their major to prepare them for entering the world of work. One of the subjects is engineering mechanics, which is the main field of science for the behavior (deflections and forces) of structures or machines against loads on the structures [5], [6]. Learning engineering mechanics in the classroom has to be considered as this subject is the basis for calculating the calculation material in other subjects. Preliminary observations were made to determine how engineering mechanics was taught in class. During the observation, questionnaires were distributed to the first-