Blended learning is gaining momentum in K-12 schools, and teachers are required to make a paradigm shift in instructional practices geared to the online learning environment but are unprepared for the unique pedagogical skills. The problem addressed in this qualitative case study was K-5 teachers' professional development is inadequate for the paradigm shift of teaching in a blended learning environment. The purpose was to explore teachers' perceptions of received professional development designed to prepare them for the paradigm shift of teaching in a blended learning environment. The theoretical framework guiding this qualitative case study were constructivism and the TPACK. Both theories share a common bond in that teachers are using 21st-century skills in applying appropriate technological and pedagogical skills in a learner-centered environment to support the current curricula. Data were electronically collected from five K-5 teachers using an online questionnaire and documentary analysis. Member checking was conducted multiple times to ensure researcher accurately presented participants' viewpoint. After the coding of data in HyperResearch 4.0, four themes emerged in answering both research questions. The themes were, first, professional development experiences of K-5 teachers; second, pedagogical blended strategies of K-5 teachers; third, technical skills of K-5 teachers; and fourth, modification of K-5 teachers' belief systems. The findings revealed that after two-three years of participating in professional development activities, teachers felt as if they were adequately prepared for the paradigm shift of transitioning to a blended learning environment but 80% lacked knowledge in pedagogical skills designed for the online learning environment. Future recommendations are to use an evaluation tool for teachers to self-assess their beliefs and design professional development activities solely to address online pedagogy. [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/en-US/products/dissertations/individuals.shtml.]