Despite the abundance of research in Modeling-based Learning (MbL) in science education, to date there is only limited research on MbL practices among K-6 novice modelers. More specifically, there is no information on how young/novice modelers' modeling enactments look so that researchers and educators have an idea of what should be expected from these novice/young modelers while engaged in MbL. Our purpose in this study was to investigate the ways in which K-6 novice modelers can engage in MbL in science, in rich modeling contexts, which feature various modeling media and tools. Using data from a variety of contexts, modeling means and tools and different student ages, we seek to develop, from the ground up, detailed descriptions of the modeling practices that K-6 students follow when involved in MbL. While using the modeling phases (e.g., construction of a model, evaluation of a model), along with their associated practices, as described in the literature for older learners and expert modelers as our basis, we followed ground research approaches to develop the descriptions of student-centered MbL. Our findings revealed that novice modelers enact certain MbL phases in a different manner than those described in the literature for older learners and/or expert modelers. We found that not only do the content and context of the various modeling phases differ, but also the sequence of these modeling phases and their associated practices, are different from those already described in the literature. Finally, we discuss how rich descriptions of MbL discourse can ultimately inform teachers and researchers about ways in which learning in science through MbL can be supported.