It is also considered plagiarism if you reuse your own work for multiple classes. To grow as a writer, you must embrace new challenges. Don't recycle previous assignments or writings. A musician can’t say, "well I practiced that piece last month, so I will just count it as today’s practice." However, if you think you have a good reason to reuse part of an old paper for a new project, just be honest and talk to your instructor about it.