Our study examines pre-service teachers' (PSTs) lived experiences designing lessons and preparing for teaching while participating in Learning Study with Variation Theory. Using a phenomenological approach, we examine the experiences of seven elementary PSTs enrolled in a mathematics education course. Data collected include transcripts of in-depth participant interviews, reflective journals, and course assignments. Our phenomenological analysis offers a general structure of participants' experiences and discusses five structural constituents particularly related to Variation Theory. Results indicate that PSTs found collaborative aspects of Learning Study challenging, and learning to theorize with Variation Theory difficult and unfamiliar. However, PSTs also found the experience valuable in helping them discern critical aspects of a complex concept, thereby helping them understand and teach mathematics in different ways. This study highlighting PSTs' lived experiences extends the limited research on using Learning Study with Variation Theory in the context of a teacher education course.