This project aims to serve the national interest by improving engineering students’ ability to model and analyze systems with physical forces acting upon them that students encounter in physics and mechanics courses. Free body diagrams are an important modeling technique because they help students understand and formulate physics and mechanics problems. Drawing free body diagrams is a foundational skill for many engineers because it is typically the first step in solving these types of problems. Students benefit by receiving timely feedback on their diagrams so that they can improve their modeling skills. This project will develop a mobile-based application that allows students to practice formulating free body diagrams in an active learning environment, using a set of problems with increasing levels of complexity. This open access application can motivate students to practice in an informal setting, help students master this modeling skill, and help students build self-efficacy early in their engineering education. The project will analyze students' use of the application and assess learning gains related to free body diagrams. The project will advance engineering education practice by providing a unique tool for students to learn how to construct free body diagrams as well as providing an opportunity to study the effects of the active learning application on student engagement, learning gains, and self-efficacy. The project will use online repositories to disseminate the mobile application to the engineering education community.<br/><br/>The three main goals of the project are: (1) to develop a mobile-based application that incorporates both sound pedagogy and motivation design to teach engineering students how to formulate free body diagrams effectively, (2) to support underrepresented students, in particular women, in improving their free body diagram skills, and (3) to increase female students’ self- efficacy related to free body diagram skills and their futures as engineers. Educational applications can be particularly useful in providing the kinds of mastery experiences that build self-efficacy by (1) providing an active learning environment in which students improve their skills by solving problems of increasing complexity and (2) providing immediate feedback. Participatory design will be employed with early undergraduate and advanced engineering students, early career engineers, and engineering faculty to design the digital learning environment, user tutorials for students, and curricular guides for faculty. The project will address the following research questions: (1) How do students engage with learning activities and immediate feedback to master the ability to draw, label, and analyze free body diagrams? (2) To what extent does providing a large quantity of scaffolded practice with immediate feedback support the development of mastery of free body diagram skills, particularly for female engineering students? (3) To what extent does the intervention increase students’ self-efficacy, particularly for female engineering students? The exploratory study will use a non-experimental mixed methods design with 300-350 students to assess educational efficacy and to establish the inclusivity of the tool for female engineers. The NSF IUSE: EHR Program supports research and development projects to improve the effectiveness of STEM education for all students. Through the Engaged Student Learning track, the program supports the creation, exploration, and implementation of promising practices and tools.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.