You are not required to make any additional purchases for BIO156. All of the required materials are provided to you. The course uses the open-source textbook, Concepts of Biology, available through OpenStax. Links to specific content in that textbook appear in assignments on Canvas. Although the OpenStax text is the prescribed text for this course, you may use whatever other sources of information you feel are helpful, considering your specific learning style. That is entirely up to you. For example, you might decide that you would benefit from additionally using a hard-copy textbook. Below I have listed just a couple examples, but there are many others, and they are entirely optional. Notice that slightly older editions of general textbooks (which are just fine) are available for just a few bucks. Please do not feel pressured at all to use any additional materials. The required materials include all of the information necessary for completing the assignments. I just want you to do whatever is best for you to personally succeed in this highly demanding course.