GoalExplain what an operating system does and what the CPU is.
New words
operating system · the main software that manages the computer and helps programs use the hardwareCPU · the central processing unit: the part that follows instructions and processes dataprocess · to work on data and change it into a result
Explanation
When you use a program, there is a helper in the middle. It is the operating system, a special kind of software. In a restaurant you tell the waiter what you want and the waiter takes your order to the kitchen. Here you and your program are the customer, the operating system is the waiter, and the CPU is the kitchen. The CPU is a piece of hardware that follows instructions and processes data. People sometimes call it the brain of the computer, but that is only a comparison: a computer cannot think like you. The operating system also keeps the computer organised, so that many programs can work together.
You and a program→Operating system→CPU
Worked examples
The restaurant comparison: customer (you and the program), waiter (operating system), kitchen (CPU). If the waiter did not carry your order, the kitchen would never know what you want.
Youssef opens a game. The game cannot talk to the CPU by itself. It asks the operating system, and the operating system tells the CPU what to calculate.
The CPU is hardware, but it only follows instructions. A cook who follows a recipe is not thinking up new dishes. The comparison “brain of the computer” means that it does the important work, not that it thinks.
Class activity
Restaurant role play. Three people: a customer (the program), a waiter (the operating system) and a cook (the CPU). The customer writes an order on paper. The waiter carries it to the cook. The cook follows it and sends a plate (a drawing) back by the waiter. Swap roles. Then say which part of the computer each role is.
Practice
1
What does the CPU do?
It follows instructions and processes data.
2
In the restaurant comparison, who is the operating system?
The waiter.
3
Put the three in order from the user to the hardware: CPU, program, operating system.
