Most elementary teachers (ETs) have majors in the humanities as undergraduates and much of the pedagogical training in a teacher preparation program tends to focus on literacy, so many ETs lack math pedagogical content knowledge and have a stronger knowledge of, and how, to teach literacy (Gonzalez-DeHass, et al., 2017; Bursal & Paznokas, 2006; Novak & Tassell, 2017; Malinsky, et al., 2006). This need for a deeper knowledge of mathematics, and how to teach it, exists during teacher training, and it is not necessarily narrowed when preservice ETs start working in the field as classroom teachers of record (Lui & Bonner, 2016; Newton, 2017; Fuller, 1997). Most ETs are not prepared to effectively teach math, and this results in an over-reliance on curriculum guides and procedural explanations of mathematics during instruction (Fuller, 1997; Lui & Bonner, 2016; Newton, 2017). Considering their training and background, it is not surprising that ETs use literacy structures in math, and this three-paper dissertation explores how a group of early-career ETs implemented math conferences as a way to support deepening student learning in math and increasing teacher understanding of student thinking during math instruction (Munson, 2018; Picha, 2022). What happens then when early-career ETs implement a new instructional practice in their classrooms? Each paper in this dissertation explores different elements of how early-career teachers implement this new practice and the ways that collaboration, school culture and climate, administrative supervision and support, professional development, and classroom structures either support successful implementation and spur teacher learning, or mire early-career teachers in the messy middle. The messy middle is the place before feeling completely competent with an instructional practice and where teacher learning is filled with approximation, failure, reflection, and success. Implications for practice and suggestions for future research result from the findings of this study. [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.]