This paper reports on the implementation of the dynamic STEM-teaching and learning technologies in teachers' classroom teaching practices resulting from their engagement in sustained professional development and classroom teaching of resources that embed carefully designed dynamic STEM-technologies within the Hungarian mathematics and science curriculum (K 1-12). The research investigated teachers' perceptions of the impact on students' mathematical understanding when teachers integrate the materials and the technology into their teaching. The sample comprised 773 mathematics and science teachers, who participated in Geomatech training over the entire period (2014-2015) of the project. Questionnaires were administered to match individual teachers' teaching schedules, and the resulting data were analysed to give summative statistics. The results indicate that teachers were able to plan tasks using Geomatech STEM resources for students to catch up with their learning, to cater to the learning needs of talented students, plan Geomatech tasks for project work and experimentation, and use them for homework tasks.