Energy is a critically important topic in the K-12 science curriculum, with many applications in the earth, physical, and life sciences and in engineering and technology. To meet the challenges associated with teaching energy, new tools and assessment instruments are needed. In this work we describe the development of a three-tier assessment instrument designed for measuring students' understanding of energy at basic, intermediate, and advanced levels. Using a bank of 372 multiple choice items targeting 14 different key energy ideas, three assessment instruments were created to test each of the three levels. These instruments were pilot tested with elementary, middle, and high school students and results were analyzed using Rasch modeling. Our findings show that by using linking items the three instruments form a common scale, allowing items and students to be compared across forms. Each instrument was found to contain items with suitable difficulties for students with a range of understandings of energy. Together these instruments form a reliable tool for measuring the growth of students' understanding of the energy concept as they progress from elementary school to high school.