The 3-step active recall method

Re-reading notes is a futile process when your aim is to remember the information and successfully apply it in exam settings. Active recall is the method you use to ensure the information sticks for a long period of time. But even active recall can be futile unless you have a structured way of implementing it. This is where the 3-step active recall method comes in, a structured method that is signature to the Levo Learning guides.

1. Step 1

   Answer up to 10 questions cold, closed book, even if you are unsure on the topic.

2. Step 2

   Answer the same questions again, but open book. Write the correct answer down even if it seems pointless.

3. Step 3

   Repeat as step 1 and answer the questions closed book again.

Worked across the OCR A-Level Computer Science specification, one subtopic at a time.

The subject, and what is assessed

OCR A-Level Computer Science (specification H446) is assessed by two written components and a programming project. Component 01 covers computer systems and Component 02 covers algorithms and programming, each lasting 2 hours 30 minutes and carrying 140 marks. The programming project carries 70 marks and is worth 20%. Calculators are not permitted in Component 01, so number representation and Boolean algebra have to be worked by hand.

Memorisation, then application

Marks are given for applying content to the question that has been set, which cannot happen while the content is still being looked up. Step 1 shows what is actually held. Step 2 puts the correct wording in front of you while the gap is still fresh. Step 3 repeats the cold test, and the difference between the first and third attempt is the part that has moved.

Every question in the guide is paired with its answer in the same document, so step 2 is done from the guide itself rather than from a separate set of notes.

What is inside the guide

Questions are grouped by topic and then by subtopic, following the OCR specification. Open a topic to see its subtopics.

Sample questions

Taken from the OCR A-Level Computer Science guide. Answer each one closed book first, then open the answer.

1. Processors: Structure, Performance and Types

   Which operations does the ALU actually perform?

   Show the answer

   Arithmetic: addition and subtraction, and multiplication and division built from repeated addition and binary shifts. Logic: AND, OR, NOT and XOR applied bit by bit. Comparisons, which are usually performed as a subtraction and set flags such as zero, negative, carry and overflow. It also performs the binary shifts themselves. The result of an ALU operation is normally placed in the accumulator.

2. Input, Output and Storage

   A national testing organisation must mark twenty thousand multiple choice answer sheets. What input device, and what limitation does it have?

   Show the answer

   Optical mark recognition. The reader detects the position of pencil marks in pre-printed boxes on the form, processing thousands of sheets an hour with almost no errors and no operator typing anything. The limitation is that it only works with specially designed forms, marks must be in the right place and made with the right kind of pencil, and it reads only the presence of a mark, not any handwriting.

3. Systems Software

   How does an operating system provide a 'platform' for application software?

   Show the answer

   It exposes a consistent set of services and interfaces (often called an application programming interface) that applications call instead of controlling hardware. A word processor asks the operating system to save a file; it does not need to know whether the storage is a hard disk drive, a solid state drive or a network share.

4. Applications Generation

   Is a translator such as a compiler application software or system software?

   Show the answer

   System software. It is a tool that supports the running and development of software on the machine rather than performing an end-user task, in the same family as the operating system, utilities and device drivers. To a professional programmer it may feel like the application they use all day, but its classification is by function, not by who uses it.

5. Software Development

   What is a software development methodology, and why does one matter?

   Show the answer

   An organised approach to building software that sets out what stages the work goes through, in what order, who is involved, and how progress and change are handled. It matters because software projects are large, involve many people, and fail far more often through poor organisation, misunderstood requirements and uncontrolled change than through anyone being unable to write the code.

6. Types of Programming Language

   What characterises the procedural paradigm?

   Show the answer

   The program is a sequence of instructions telling the computer step by step what to do, in a stated order, using the three basic constructs of sequence, selection and iteration. Data is held in variables that the instructions read and change, and the instructions are grouped into procedures and functions that can be called from elsewhere. It is imperative: the code says how the task is to be carried out.

7. Exchanging Data

   What is compression, and what is it actually for?

   Show the answer

   Compression is the process of reducing the number of bits needed to store or transmit a file. It is used to save storage space, to reduce the bandwidth a transfer consumes, and so to shorten download, upload and streaming times. It can also reduce cost where storage or data transfer is charged by volume.

8. Networks

   Which protocols operate at each layer of the TCP/IP stack?

   Show the answer

   Application layer: HTTP, HTTPS, FTP, SMTP, POP3, IMAP, and DNS queries. Transport layer: TCP and UDP. Network layer: IP, which carries the addressing and routing. Link layer: the technologies that move frames over the physical medium, such as Ethernet on cable and Wi-Fi over radio.

Questions about this guide

Other OCR A-Level guides

All OCR A-Level guides · All A-Level guides