National Science Education Standards
Life Science Content Standard C:  As a result of their activities in grades 5-8, all students should develop understanding of structure and function in living systems.  Principles that underlie this standard include structure and functions of cells, tissues, organs, systems for movement, control, and coordination.  A behavioral response requires coordination and communication at many levels, including cells, organ systems, and whole organisms. (pp. 155-157).

AAAS Benchmarks
Human Organism Basic Functions Grades 3-5: At this level, children can begin to view the body as a system, in which parts do things for other parts and for the organism as a whole.  Models help children to see and touch the internal organs and to know where they are located in the body. They can begin to understand that each organ affects and is affected by others.  By the end of 5th grade, students should know that the brain gets signals from all parts of the body telling what is going on there.  The brain also sends signals to parts of the body to influence what they do. (p. 136)
Human Identity Grades 6-8:  By the end of the 8th grade, students should know that human beings have body systems for providing coordination of body systems. (p. 129)  Students can now develop more sophisticated understandings of how organs and organ systems work together.  This includes circulation of and transportation by blood, and the carrying of messages by nerves to help the organism respond to its environment. Asking What if? questions such as What might happen if some other parts weren’t there or weren’t working? can stimulate students to reflection connections among organs. (p. 137)  By the end of the 8th grade, students should know that interactions among the senses, nerves, and brain make possible the learning that enables human beings to cope with changes in their environment.

National Science Teachers Association 
Scope Sequence and Coordination
At the 6-8 grade level, the curriculum should emphasize the human organism. (p. 48)  Students should explore the different systems.  From activities they should see a correlation between healthful living and system maintenance.  Designers and teachers must avoid a mindless march through the body systems. Coordination with topics from other disciplines results in more dynamic experiments.  For example, activities could relate circulation to principles of pressure, muscles and skeletal structures to machines and gas exchange. (p. 49)

Nebraska Science Standards
Grades 5-8 At the middle school level, students expand their scientific inquiry skills through knowledge, observations, ideas, and questions. Middle school students will begin to recognize the relationships between explanation and evidence.  They understand that background knowledge and theories guide the design of investigations, the types of observations made, and the interpretation of data.  Student investigations will shape and modify students background knowledge. (p. 24)