Computational thinking (CT) has been given recent attention suggesting that it be developed in children of all ages. With the creation of K-12 computer science standards by the Computer Science Teacher Association, states such as Massachusetts and Washington are leading the nation in adopting these standards into their school systems. This seems somewhat premature, when there are so few measures of computational thinking or computer programming skills that can be applied easily in a K-12 setting to assess outcomes of such state-wide initiatives. Through funding from the National Science Foundation, we developed an analysis tool to efficiently capture student learning progressions and problem-solving activities while coding in Scratch, a popular visual programming language developed by MIT Media Lab. Our analysis tool, the Functional Understanding Navigator! or FUN! tool, addresses the need to automate processes to help researchers efficiently clean, analyze, and present data. We share our experiences using the tool with Scratch data collected from three different week-long summer Scratch Camps with students in grades 5 to 8. Based on our preliminary analyses, we share important considerations for researchers interested in educational data mining and learning analytics in the area of assessing computational thinking. We also provide links to the publically available FUN! tool and encourage others to participate in a community developing new measures of computational thinking and computer programming.