This explanatory case study proposed an in-depth description of EFL co-teaching practice at the Laura Vicuña’s institution preschool grades through the self-contained teachers’ insights. The qualitative research was carried out with 2 participants groups: 2 preschool teachers and children from Transition 1 and Transition 2 of this public school in which they developed 2 different instructional designs assigned in three progressive cycles to face kids’ lack of previous exposure to the English language and teachers’ absence of support and training related to EFL teaching in very young learners. Therefore, this study’s process was supported by co-teaching theory, preschool education considerations, children’s comprehensive learning, and visual literacy in EFL focused on very young learners. Thereon the notebooks for kids and teachers were created and also, the audiovisual material was produced. Subsequently, co-teaching provided supportive relationships among educators during the pedagogical intervention in which knowledge, experience, and collaboration encouraged and allowed self-contained teachers to enhance their language proficiency level as well as their EFL teaching practice.