The novel assessment models and studies developed in this work provided new insight on effective teaching practices in chemistry classrooms and laboratories through the framework of constructivism. Each project aimed to promote greater levels of understanding and inspire interest in chemistry, both of which are great challenges within the U.S. educational system. Assessment drives learning, so appropriate tests are essential to good courses. However, large classes often make written exams impractical. A multiple-choice test of conceptual knowledge in general chemistry was created and validated to provide the chemical education community with a reliable and functional tool that correlates with open-ended General Chemistry exams. Large classes make active-learning implementation challenging, as not all students can participate. Students in a large General Chemistry course taught via active-learning were studied through surveys and interviews. The data revealed that “silent” students are engaged in the active-learning experience, yet “vocal” students outperform silent students on measures of conceptual understanding in chemistry. The motivation behind being vocal suggested students participate in order to improve their grade, and while doing so, also see the benefit to their learning. Another mixed-methods study focused on the traditionally formatted General Chemistry Laboratories. Initial data on student expectations lead to the creation of a pilot lab section and ultimately a new format of the labs with the inclusion of a discussion session. The changes resulted in the students being better prepared, focusing on the content rather than the process of the labs, and reporting better understanding of chemistry due to labs. Two novel laboratory experiences were also developed to promote conceptual understanding, and their creation and use are outlined. The impact of a professional development program on high school chemistry courses was analyzed via interviews, teacher observations and a case study. The professional development exposed teachers to novel chemistry teaching practices of inquiry-based concept development and active-learning methods. The case study showed implementation of the instructional strategies to be successful within an existing exemplary chemistry classroom. Each of these projects advanced best practices in teaching chemistry by expanding the current understanding of teaching concepts and analyzing applications of research-based pedagogies.