Although there has been a significant increase in the number of charter schools, little is known about their science education programs from the science teachers' perspective. Also, the COVID-19 pandemic created limitations for all participants that required new untested approaches that varied depending on circumstances. The first study in this dissertation explored secondary charter school science teachers' perceptions related to their schools' science programs. With the use of the "Science Laboratory Classroom Facility and Science Instructional Materials Survey" and a semi-structured interview protocol, secondary charter school science teachers' (N=105) perceptions of laboratory equipment, safety equipment, facilities, science standards, and autonomy were examined, and a subsample of teachers (n=21) was interviewed. The findings showed that charter school science teachers taught in facilities that were inadequate for science laboratory instruction. Many teachers lacked the most essential laboratory and laboratory safety equipment. Other findings included a high degree of reported autonomy related to instructional decision-making. These results suggested that the quality of charter school science programs could be strengthened by adequately funding science laboratories, equipment, safety equipment, and engaging science teachers in program and facilities planning. The second study utilized a subsample of teachers interviewed in the first study to examine charter school secondary science teachers' online teaching in response to COVID-19. Specifically, this study explored teachers' instructional approaches, teaching constraints, and work-related stressors with a semi-structured interview framed within a Community of Inquiry framework. The findings were that greater planning, training, hardware, and software infrastructure preparation, guidance on instruction formats or standardization, peer support systems, and communication were needed to address future crises such as COVID-19 and to enhance similar urgent transitions to online learning. Implications for future research and pedagogy are discussed. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]