This work applies to Computer Science (CS) K12 Education through a user experience and human-centered design and research approach. Due to the increase in use of technology, CS courses are important opportunities for K12 students to explore. In order to support the courses added to K12, in-service teachers lacking CS background are stepping up and tackling the CS field. To prepare in-service teachers to teach CS K12 courses, such as Advanced Placement Computer Science Principles (APCSP), curriculum providers host professional developments (PDs) for teachers to learn the content of the curriculum, pedagogies for teaching computing, and methods to support their students into technology. As novice CS teachers begin teaching their new field, many want continued support and community as they learn the new material. In this proposal, I present five studies exploring how to assist in-service teachers with teaching CS and computing in their classrooms when using block-based languages. For my work, I first learned about teacher needs by redesigning teacher professional developments. This motivated me to develop new ways to support teachers integrating computing and teaching computing in K12. In the Teacher Professional Development experience report, I start by assisting teachers attending an Advanced Placement CS Principles (APCSP) Beauty and Joy of Computing (BJC), a curricula for the AP CSP course, Professional Development (PD) by redesigning the PD to more align with typical PD standards. In the Initial Design of GradeSnap user experience sprint study, I interviewed block-based language (BBL) graders to develop an understanding of what elements to have in a BBL grading tool as well as the flow of the tool. In the Initial Development Prototype and usability study, I discuss the phases of development and what elements have been tested thus far to ensure the usability and usefulness of GradeSnap. In the Grading BJC Programming Labs study, I investigate teachers individually, comparing their created rubrics and their grading habits when grading with without a rubric and with a rubric they have created. Additionally I discover common pain points for teachers when grading BBL projects in their current grading environment. In the Grading with GradeSnap study, I compare how the same teachers' grading habits are impacted by GradeSnap, as well as how GradeSnap addresses the teachers' pain points or what further needs to be done to ease the tedious task of grading BBLs. The contributions of this work furthers research into effective K12 computing teacher professional development designs and pedagogical models, understanding of K12 computing and non-computing teachers' grading methods of BBLs, and a new tool for teachers to grade BBLs. Additionally, this research will contribute a new user experience research method for designing human-centered applications with a small research team. [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.]