This paper explores in-service teachers' experiences integrating Struggly, a digital mathematics platform, into their classrooms through a structured professional development program. Grounded in the principles of Mathematical Mindsets, Struggly offers low-floor, high-ceiling tasks designed to enhance number sense, conceptual understanding, and problem-solving skills for students in grades 1 to 8.

The study involved 24 teachers who participated in a professional development model based on a study-plan-teach-reflect-extend framework. Teachers analyzed and implemented Struggly tasks, reflecting on their experiences and challenges. Data sources included lesson plans, teaching experiment videos, reflection journals, and extension plans, which were analyzed to identify key insights.

Findings indicate that teachers valued Struggly for its accessibility, engaging design, and ability to foster a growth mindset through productive struggle. They also deepened their understanding of effective mathematical tasks, recognizing the importance of open-ended problems, multiple solution strategies, and cultivating a positive relationship with mistakes. Additionally, teachers reflected on the strategic use of technology in mathematics instruction, highlighting the benefits of immediate feedback and adaptive learning while acknowledging challenges related to equitable access to digital tools.

This study is part of a broader research effort exploring how mathematics teacher educators, through the Computing Integration Teacher Education (CITE) lens, can design and implement artifacts that support teachers in using technology strategically in mathematics instruction. The paper discusses how teachers used Struggly as an instructional tool and a context for designing and refining mathematical tasks. It concludes with implications for professional development, highlighting how teachers can leverage technology to create more interactive and student-centered learning environments in school mathematics.

Keywords: Mathematics Education, Strategic Use of Technology, Professional Development, Mathematical Tasks, Mindsets.