Investigation One introduces students to the concept of physical fitness. Through the use of models and charts, students become familiar with the function of the cardiovascular and respiratory systems and begin to understand the interdependence of the two systems. Students will also observe their cardiovascular system before and after exercise by obtaining and calculating their heart rate.

In Investigation Two, students will continue to find the correlation between physical fitness and the cardiovascular and respiratory systems. Through experimentation and observation, students will determine that exercise increases heart rate and respiratory rate. This leads students into creating a model of a “strong” heart and a “normal” heart, illustrating that increased cardiovascular fitness is one key advantage of exercise over a long period of time.

During Investigation Three, students will begin their exploration of the musculo-skeletal system. While performing exercises, students will determine the ways in which their joints and muscles are involved in movement. Through these exercises, students will conclude that muscles are organized in pairs, with each muscle in the pair controlling opposing motion. In addition, students will perform experiments leading them to an understanding of muscular fitness, both in muscle flexibility and endurance.

Investigation Four introduces students to the relationship between energy balance, nutrition, and exercise. Students continue their exploration of the various body systems involved in physical fitness by examining the role of the digestive system in relation to the cardiovascular, respiratory, and musculoskeletal systems. Through the use of a lever model, students will explore how energy input and energy output influence energy balance. Students will discover the importance of varying the intensity of exercise and making wise food choices in maintaining energy balance and overall physical fitness. 

In Investigation Five, students will examine the influence of practice on performance and will be introduced to the application of the principles of physics to performance and technique. Students will discover that performing a new task repeatedly will improve the performance of the muscles involved in the task and will learn that repetition of skills leads to improved muscle coordination. Students will discover through experimentation that the kinetic energy of muscle can be used to improve performance. Students will also use experimentation to explore the use of torque and body mass location to improve technique, thus enhancing overall performance during physical activity. 

Investigation Six consists of a performance assessment designed to evaluate students’ understanding of the science concepts addressed in the first five Investigations of the CELL. During this exploration, students will design and begin to implement a fitness plan to increase cardiovascular and muscular fitness.