Research has consistently shown that active problem-solving in a collaborative environment supports more effective learning than the traditional lecture approach. In this study, a flipped classroom format was implemented and evaluated in the chemistry majors' sequence at Purdue University over a period of three years. What was formerly lecture material was presented online outside of class time using videos of PowerPoint lectures with a voice-over. In-class time was devoted to collaborative problem solving based on the Student Centered Active Learning Environment with Upside-Down Pedagogies (SCALE-UP) approach, which has been shown to increase student exam scores and passing rates. The purpose of this proof-of-principle study was to look at quantitative measures of student performance in the flipped versus the traditional lecture approach of this chemistry course. Three years of results using ACS standardized exams showed that students' ACS general chemistry exam scores in the flipped class were significantly higher by almost one standard deviation when compared with the students' previous scores in the traditional class. Analysis of open-ended surveys given to students at the end of the course showed that the majority of students responded positively to the format, listing a variety of benefits, drawbacks, and ways to improve that can inform future implementations.