The purpose of this chapter is to examine science and engineering practices in detail. The analysis of the practices makes connections with the practices’ disciplinary characteristics and decomposes the learning tasks that can be accomplished to master science and engineering practices. A better understanding of how science and engineering practices represent (or do not represent) disciplinary characteristics elevates the practices beyond the steps students follow to get an “answer” for their investigation. Similarly, this chapter will examine practices through the lens of process and outcomes goals so that teachers can use the decomposed learning tasks in each science and engineering practice to model disciplinary work to support students.