This paper examines the partial inversion of ME 450, an introductory dynamic system modeling course at Penn State University. To invert or 'flip' a course is to (i) introduce students to core concepts outside of class time, thereby (ii) creating more room for in-class active learning. Typically students watch lecture videos as homework, then solve related exercises in teams, with instructor assistance, in the classroom. In the Fall semester of 2013, the authors flipped ME 450, but only partially: the first 30% of the course was flipped, while the remainder was taught through a traditional lecture format. This allowed the authors to observe some distinctions between the two formats. The goal of this paper is to describe the above classroom flip to the system dynamics and control community, and share some of the associated firsthand observations. The subjective nature of these observations is indisputable, and the paper should therefore be viewed as a record of experiences rather than rigorous summary of objective findings. Penn State University's Leonhard Center for Enhancement of Engineering Education has conducted an internal review board (IRB)-approved, objective assessment of the ME 450 course flip, the results of which complement this paper but are intended for independent dissemination.