The Theory of Errors . Measurement of linear body sizes. Calculation of volume. Laboratory work No1 on mechanics for bio students” by the team of authors is the most important teaching aid, which will become an indispensable assistant for students studying mechanics and experimental physics in the field of biological sciences. This book is not just a theoretical guide, but a practical tool that combines the basics of accurate measurements, error analysis and practical skills necessary for laboratory work in the field of biomechanics and biophysics. What makes this book special? First of all, it reveals the subtleties of measuring linear body sizes, which is a fundamental task in biological research. The author's team carefully examines the methods and tools used to obtain the most accurate data, and also teaches to correctly assess and take into account errors, which is especially important in experimental science. The book details the process of measurement, ranging from simple methods to more complex approaches, making it useful for both beginner students and those who already have experience in laboratory work. Particular attention is paid to the calculation of the volume of bodies - the most important parameter in biomechanics and biophysics. Students will learn how to correctly apply formulas and methods to determine the volumes of different biological objects, whether they are cells, organs, or whole bodies. The book presents practical recommendations for processing the data, which helps to form skills of analytical thinking and accuracy in working with measuring instruments. The Theory of Errors . Measurement of linear body sizes. Calculation of volume. Laboratory work No1 on mechanics for bio students" is intended for students studying in specialties related to biology, medicine, biomechanics and physiology. It will be especially appreciated by students who are just starting out in experimental science, as well as those who want to deepen their knowledge in the field of accurate measurements and learn how to correctly interpret the results. Age audience - from undergraduate students to young scientists who want to systematize and expand their practical skills The author's style of the book is distinguished by clarity, logic and accessibility of the presentation of complex concepts. It combines scientific rigor with practical advice, making the material easily digestible and motivating for further study. The book also contains references to classical and modern methods of measurement, which allows the reader to get acquainted with the history and current trends in the field of accurate experiments. This book is part of a series of laboratory papers on mechanics for bio students, and it holds a special place due to its practical bias. It details not only the theoretical foundations, but also specific examples, which makes it a valuable tool for conducting your own research and laboratory experiments. In general, "The Theory of Errors . Measurement of linear body sizes. Volume calculation" is the key to developing the skills of accurate measurements and analytical thinking necessary for successful scientific activities in the field of biomechanics and biophysics. If you are looking for a book that will help you understand how to measure and analyze biological objects correctly, avoiding errors and errors, this work will become your reliable companion. It is perfect for those who want not only to master the theory, but also to learn how to apply knowledge in practice, making their research accurate and reliable. In today's world of biological sciences, where measurement accuracy plays a crucial role, "Theory of Errors" will help you become a real professional in the field of experimental biomechanics.