Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Define key biomechanical principles.
• Explain how these principles apply to physical activity.
• Analyse how to use these principles to improve performance and prevent injuries.

Lesson summary

This lesson introduces the fundamental biomechanical principles that govern all human movement. Biomechanics is the study of how forces affect the living body. Understanding these principles is not just for elite athletes like the Black Stars or our Olympic team; it is essential for anyone who wants to move more efficiently, improve their performance in any sport (even during inter-house competitions), and most importantly, prevent injuries in everyday activities like carrying a bucket of water or farming. By learning why our bodies move the way they do, we can unlock our potential and stay safe.

Lesson notes

Here are the core scientific principles we will be exploring. We will break them down with simple explanations and local examples. Concept 1: Stability and Balance Stability is the ability to resist being moved or having your balance disturbed. It is crucial for almost every sport and many daily tasks. Two main factors affect stability: Center of Gravity (COG): This is the imaginary point in the body where all its mass is evenly distributed. In a standing person, it is usually around the navel area. Principle: The lower the Center of Gravity, the more stable the object or person. Base of Support (BOS): This is the area on the ground enclosed by the points of contact with the ground. When you stand with your feet together, your BOS is small. When you spread your feet apart, your BOS becomes wider. Principle: The wider the Base of Support, the more stable the person.

Relationship: To achieve maximum stability, a person should have a wide Base of Support and a low Center of Gravity. Ghanaian Example: Think of a goalkeeper like Richard Ofori preparing to save a penalty. He crouches down (lowering his COG) and spreads his feet apart (widening his BOS). This makes him very stable and ready to move powerfully in any direction. A traditional wrestler ('Asafo') takes a low, wide stance to avoid being thrown to the ground. Concept 2: Motion (Newton's Three Laws) Sir Isaac Newton's laws explain how and why things move. Newton's First Law: The Law of Inertia Explanation: An object will remain at rest, and an object in motion will stay in motion with the same speed and in the same direction, unless acted upon by an external force. Inertia is the resistance to a change in motion. Example: A football placed on the penalty spot will stay there forever unless a player kicks it (external force). Once kicked, it will keep moving until friction from the grass and air resistance (external forces) slow it down and stop it. Newton's Second Law: The Law of Acceleration (F=ma) Explanation: The acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass (Force = mass × acceleration). Simply put, to move something faster, you need to apply more force. Example: If a player wants to kick a football with great speed (high acceleration), they must apply a very large force with their leg. Kicking a heavier object like a medicine ball with the same force would result in less acceleration. Newton's Third Law: The Law of Action-Reaction Explanation: For every action, there is an equal and opposite reaction. Forces always come in pairs. Example: When a high jumper pushes down hard on the ground (the action), the ground pushes back up on them with an equal and opposite force (the reaction), propelling them into the air. A volleyball player does the same to jump for a spike. Concept 3: Levers in the Human Body Our body uses bones, joints, and muscles to create levers to move. A lever system has three parts: Fulcrum: The pivot point (our joints). Effort: The force applied by the muscle. Load (or Resistance): The weight being moved (e.g., a ball, a javelin, or the weight of the body part itself).

There are three classes of levers, but the most common in the human body for sport is the Third-Class Lever. Third-Class Lever: The Effort is applied between the Fulcrum and the Load. Characteristics: This type of lever does not provide a mechanical advantage for force, but it provides a huge advantage for speed and range of motion. Example: Kicking a football. Fulcrum: The hip joint. Effort: The quadriceps muscles contracting to straighten the knee. Load: The football and the lower leg. A small, powerful contraction of the quadriceps muscle results in the foot moving a large distance very quickly, allowing for a powerful kick. Most athletic movements like throwing and striking use third-class levers.

Guided Practice (With Solutions)

Evaluation guide

• Apply biomechanical principles in physical activity
• Experiential Learning: Learners work in groups to analyse videos on biomechanical
• principles and indicate how they are applied in physical activities
• Exploratory Learning: In groups, select and apply biomechanical principles in