【Shanghai Edition】Junior High School Science Grade 8 Lower Semester

This textbook is designed for the second semester of eighth-grade science, using an interdisciplinary integration approach. It covers core topics in mechanics (forces, simple machines, work), biology (biological movement, neural-hormonal regulation, biological reproduction), and Earth sciences (weather and climate).

Crossing the boundaries of physics, biology, and meteorology—embark on a journey of integrated scientific exploration.

Author: Shanghai Education Press

Acknowledgments: Reviewed by the Ministry of Education, 2013

1. Students will be able to identify the three elements of force and skillfully use force diagrams and schematic representations to depict the magnitude, direction, and point of application of forces.
2. Students will be able to conduct experiments to investigate the relationship between spring extension and applied force, mastering methods for calculating and analyzing gravity (G=mg) and friction.
3. Students will understand the content of Newton’s First Law, apply knowledge of inertia to explain real-life phenomena, and determine the forces acting on objects in equilibrium under two forces.
4. Students will be able to describe the conditions for balanced forces and perform calculations involving the combination of forces along the same line.
5. Students will understand the working principles of fixed pulleys, movable pulleys, pulley systems, and inclined planes, and be able to calculate pulling force, work, power, and mechanical efficiency.
6. Students will be able to identify different forms of mechanical energy and use the law of conservation of energy to analyze energy transformations during object motion.
7. Students will be able to identify and describe the structural components of skeletal muscle (belly and tendon) and its source of power.
8. Students will understand and explain the mechanical process by which skeletal muscles contract to pull bones around joints, as well as the coordinated interaction between flexor and extensor muscle groups.
9. Students will provide examples illustrating the movement characteristics and structural basis of various invertebrates (e.g., paramecium, earthworms, insects).
10. Students will accurately distinguish between endocrine and exocrine glands and name major human endocrine glands and their respective hormones.