# Computing in Primary Schools: teacher survival kit SECOND LEVEL

This series of resources is designed to lay the foundations of learners developing an understanding of what computers are and how they work. This level introduces the concepts of:

• computers are machines designed to do jobs
• computers have instructions to tell them how to do those jobs

The learning will be about identifying the different jobs computers do in their lives and the wider world. It is important to link between the physical computer (parts) and the instructions (apps/software) that controls them.

Educator notes

Computer systems have a common model, the von Neuman architecture, which almost every machine is designed with:
inputs – memory/processor/storage – outputs

The processor runs the software, executing one instruction at a time. The instructions (for every app running) is stored in memory until the processor is ready for the next line. So too, are any inputs until processed. Anything that needs to be kept after the computer is turned off is ‘saved’ in storage, such as a hard disk or ‘the cloud‘.

Computers can be connected to each other to share data and resources. The internet is the biggest and most common computer network in the world. Information is sent between computers using cables under the ground and under the sea. Although we often think of mobile devices being ‘wireless’ they use radio waves to send information a short distance to a router (WiFi) or transmitter (3G, 4G or 5G).

The world wide web or ‘web’ is the most common user-friendly software used to navigate the internet (the hardware). This is often done using web browsers, such as Edge, Chrome or Safari.

Computers use a voltage (on or off) to activate or not activate a series of switches. This is how a processor processes the code. IS is represented by a (high) voltage and the computer processes this using the number 1. IS NOT is represented by no or low voltage and the computer understands this to be the number 0. This is how every computer works.

The binary number system can only represent the number 0 or 1 in each place value. The first four place values being 8, 4, 2, 1 as opposed to our denary system which can represent 0-9 in each place, with the first four places being 1000, 100, 10, 1.

Modern computers use millions, if not billions, of microscopic switches, to make millions of decisions (selections) per second. This gives the illusion that computers can do lots of things at one time, such as run the operating system, web browser, play music, and display on the screen.

The main bit for learners is that computers are simple machines that have complicated processes. In order to make them easier to use Grace Hopper created the first ‘high level code‘ that looked like English. This is what we generally mean by code. Block-based code is an even higher level of code making it even easier to understand.

Explaining the insides of a computer
Computer networks – the internet
How computers work – code

How is all our digital data stored? – BBC Bitesize BINARY and MEMORY

Complex? Yes!

So we made code as a way to use language and words to give the computer instructions even though it only understands 1s and 01

Grace Hopper – invents language- based code

Checking learning

Learners should be able to describe the von Neuman model of a computer:
input, process, memory, storage and output

Learners should be able to use block-based code to create a short set of instructions in the correct sequence and using a selection and creating a variable:

Learners should be able to predict what a set of instructions in block-based code might do and fix it: