Students in Mrs. Cornell's kindergarten class shared their observations about what happened when drops of water were placed on different types of wood. The students were engaging in a science lesson focusing on the observable properties of wood, an activity from the FOSS Wood and Paper science module. This lesson is one of many that Mrs. Cornell designed to lay the foundation for the second-grade disciplinary core idea, PS1.A., Matter exists as different substances that have observable properties. The lesson also begins to develop an understanding concerning the strengths and weaknesses of materials, something that can be used later when students participate in design challenges as specified in the performance expectation K-2-ETS1-3 (Achieve Inc. 2013; see Connecting to the Standards). Not only were the students engaging in inquiry, but they were also working toward meeting the learning intentions set forth by their teacher. Teachers of kindergarten through grade 4 have been implementing research-based formative assessment strategies in their daily practice as a result of attending a week-long Institute for Assessment provided by ASSET STEM Education through a federal Investing in Innovation grant. In this article, the authors focus on the role that formative assessment plays in one kindergarten classroom in Berlin Brothersvalley School District in Somerset County, Pennsylvania. They also take a look at the assessment tools used by the teacher to gauge student understanding as well as different products of assessment that provide evidence of student learning.