The problem investigated in this study was the decline in student achievement since the implementation of project-based learning (PBL) by the third- through sixth-grade teachers at the local elementary school. The purpose of this basic qualitative study was to investigate teachers' perceptions at the study location about their knowledge of PBL and its application in third- through sixth-grade classes. The study was rooted in Jean Piaget's cognitive learning theory of constructivism. The study location was an urban school district in the Southern United States. Data on teacher perceptions was gathered through structured interviews, conducted via Zoom, with eight elementary teachers in third- to sixth-grade. Inductive coding, code landscaping, and code mapping were used to generate five themes based on participating teachers' experience with PBL. Results indicated that experienced teachers were able to speak specifically to their instructional practices and beliefs, while inexperienced teachers felt they were unable to adequately provide information. One commonality was that all participants said they needed a strong formal training and ongoing support structure to ensure effective instructional fidelity of state standards in PBL units. A 3-day professional development was developed to support teachers in planning and implementing PBL to ensure instructional fidelity of state standards throughout their units. This study could create positive social change by assisting administrators with supporting teachers with planning effective PBL units. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]