Your course fees for BIO181 have already paid for access to an electronic version (eText) of Principles of Biology by Brooker, et al. This textbook will be very useful for completing Connect Homework (described on Canvas). You may also use the Brooker eText as a general study aid, of course, but there is no "required" textbook. All of the material for examinations comes directly from my lectures, so the archive of recordings of my lectures should be viewed as the primary source of study material. Any textbook that you choose to use can supplement the information in my lectures, but the lectures are required, whereas textbook readings are optional. Further, if you choose to read a textbook to clarify points that I make in my lectures, then the choice of textbook is yours, whether it is the Brooker textbook, some other general biology textbook, or no textbook. When it comes to textbooks, the important thing is to choose one that you find personally useful. I have listed a couple possibilites below, but there are many others. Just keep in mind that my lecture recordings are what you should focus on.