Science and engineering practices (SEPs) and crosscutting concepts (CCs) constitute a significant part of "A Framework for K-12 Science Education" (NRC 2012). As teachers, the role of the authors is to highlight the pivotal role that both scientific knowledge and the practices used to generate knowledge play in learning. This article shares how assessment probes can situate learning, drive firsthand experiences, and support deeper conceptual understanding. This fifth-grade lesson targets two interrelated performance expectations (PE) that state students can, "measure and graph quantities to provide evidence that regardless of the type of change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved (5-PS1-2) and "conduct an investigation to determine whether the mixing of two or more substances results in new substances (5-PS1-4)" (NGSS Lead States 2013). The activities help confront student misconceptions about chemical reactions.