Science & Technology — Force and Energy

Subtopic: Machines (for age 11, Kenya)

What is a machine? A machine is any tool that helps people do work more easily. Machines use force and energy to move or change things. Simple machines are parts of many tools and help us lift, push, pull or cut with less effort.

Six Simple Machines

• Lever — a stiff bar that moves around a point (fulcrum). Example: seesaw, a plank used to lift a heavy rock.
• Wheel and axle — a larger wheel fixed to a smaller axle. Example: bicycle wheel, cart wheel.
• Pulley — a wheel with a rope. Example: drawing water from a well with a bucket.
• Inclined plane — a sloping surface (ramp). Example: a ramp used to load sacks onto a lorry.
• Wedge — two inclined planes back to back used for cutting or splitting. Example: panga (machete), axe.
• Screw — a twisted inclined plane around a rod. Example: jar lid, some hand pumps.

Why machines help

- They reduce the force we need (so we do less hard pushing or lifting).
- They can change the direction of a force (for example, a pulley lets you pull down to lift up).
- They can make things move faster or more easily.

Easy diagrams

Local examples you know

• Drawing water from a borehole with a pulley or hand pump.
• Using a wheelbarrow to move soil or crops at the farm.
• Using a panga (machete) or axe — these are wedges that split wood or cut grass.
• Using a ramp to load maize bags into a lorry at the market.

Simple classroom activities

1. Build a lever: Use a ruler, a pencil (fulcrum) and a small object. Move the pencil to see how lifting becomes easier.
2. Make a pulley: Use a thread and a spool. Hang a small cup and pull the free end of the thread.
3. Compare ramp vs lifting: Try moving a toy up a ramp and lifting it straight up. Which takes more force?

Key words (with simple meanings)

• Force — a push or a pull.
• Effort — the force you apply.
• Load — the object you want to move.
• Fulcrum — the point a lever turns on.
• Mechanical advantage — how much a machine helps you (makes the effort smaller).

Safety tips

Always ask a teacher or adult before using tools. Keep fingers away from moving parts, wear shoes when handling heavy loads, and be careful with sharp tools like a panga or axe.

Quick quiz (try answering)

1. Which simple machine is used in a bicycle wheel?
2. How does a ramp (inclined plane) help when loading heavy bags?
3. Name one tool in your home or farm that is a wedge.

Well done — now try to spot simple machines around your home and school!