Each year, in middle and high school classrooms, secondary science teachers introduce their students to the periodic table of elements (herein the periodic table). According to the Next Generation Science Standards (NGSS Lead States, 2013), one of the performance expectations states that high school students should be able to, "Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy levels." Thus, building an understanding of how elements vary in properties is foundational knowledge for middle grades science students. In this paper, we provide context around the importance of having middle grades students participate in the scientific practices of evaluating data and model-building, just as Dimitri Mendeleev and his contemporaries did. Having students use data on elemental properties to find patterns helps them develop their understanding of the nature of scientific discovery as well as aid in their comprehension of the periodicity of elements. Middle grades students are rarely engaged in the process of scientific model-building (Schwarz et al., 2009). Involving learners in model development leads to deeper understanding of key models in science and the nature of disciplinary knowledge in science (Lehrer & Schauble, 2007). By explaining this novel lesson, we evidence how this activity engaged students in the practices of scientists as they learned about this fundamental model.