The Building Systems from Scratch project integrates systems and computational thinking into middle school learning about climate science by interweaving game design and climate science learning. The project is based on the idea that when young people build games, they construct knowledge at the same time. We conjecture that students learn science and computation practices, and the dynamics of climate science, better by building games than by direct instruction or student inquiry alone. The instructional approach includes a view of students as knowledge producers, and of classrooms as networks of expertise distributed among students. The project is researching this learning environment and, in addition, also researching how teachers can be supported to deepen their integration of computing into science instruction.