The haptic paddle is a force-feedback joystick used at several universities in teaching System Dynamics, a core mechanical engineering undergraduate course where students learn to model dynamic systems in several domains. A second goal of the haptic paddle is to increase the accessibility of robotics and haptics by providing a low-cost device for middle and high school teachers and students, a goal which has been hindered to date by the lack of low-cost electronic solutions for motor control and computer interfacing. Prior assessments of the learning enabled by the paddles at the college level have been qualitative, consisting of anecdotal case studies illustrating student and educator belief that they enhance learning and increase student enthusiasm. In this paper, we describe haptic paddle design enhancements and provide a formal assessment of student learning when interacting with haptic paddles. Design enhancements seek to enable broad dissemination and improve the student experience by making the paddle less expensive (less than $100 for a complete system including electronics) and easier to use. Our formal assessment quantifies if and when learning occurs in a System Dynamics course featuring haptic paddle laboratories, via multiple choice quizzes presented at various time points to measure learning in the lecture, in the lab, during lab report writing, and at the end of the semester.