Students will revisit the algorithms such as searching and sorting algorithms (bubble sort, insertion sort, merge sort, quick sort), with reference to Big-O notation in terms of time and space complexity, standard algorithms for depth-first and breadth-first graph traversals, optimisation algorithms, such as Dijkstra’s shortest path algorithm and the A* algorithms have been applied to their NEA projects.
A sequence of steps designed to perform a particular task. An algorithm may be constructed to describe the operation of a complete system or to describe a particular part of it.
Used in computer science to describe the performance or complexity of an algorithm. Big-O specifically described the worst-case scenario, and can be used to describe the execution time required or the space used (e.g. in memory or on disk) by an algorithm.
A simple algorithm popular with inexperienced programmers. It is inefficient when sorting large amounts of data as the time taken is related to the square of the number of items. If 10 items take 1ms then 100 times will take 100ms (this is 10 times the number of items and so the time will be 102 or 100 times longer).
A simple sorting algorithm that builds the final sorted array (or list) one item at time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort.
A type of divide and conquer algorithm that was incited by John von Neumann. First the list is divided into the smallest unit (1 element), then each element is compared with the adjacent list to sort and merge the two adjacent lists. Finally all elements are sorted and merged.
A type of divide and conquer algorithm which sorts the given sequence in place meaning that it doesnt require extra storage as would be needed in a merge sort. The basic idea is dividing the sequence into two sub-lists around an element which is called the pivot such that all elements in the lower sub-list are less than the value of the pivot element and all elements in the higher sub-list are greater than the pivot element.
A graph search algorithm that solves the single-source shortest path problem for a graph with non-negative edge path costs, producing a shortest path tree. This algorithm is often used in routing and as a subroutine in other graph algorithms. In practice in picks an unvisited vertex with the lowest-distance, calculates the distance through it to each unvisited neighbour, and updates the neighbours distance if smaller. It the marks the visited when done with neighbours.
Widely used in pathfinding and graph traversal, the process of plotting an efficiently traversable path between points, called nodes. A* uses a best-first search and finds a least-cost path from a given initial node to one goal node (out of one or more possible goals). As A* traverses the graph, it follows a path of the lowest expected total cost or distance, keeping a sorted priority queue of alternate path segments along the way.
A particularly efficient search method. It only works if records in the file are in sequence. A binary search involvers accessing the middle record in the file and determining if the target record has been found or, if not, if it is before or after in the sequence. This process is repeated on the part of the file where the target record is expected, until it is found.
Involves examining each entry in turn in the file until the time is found or the end of the file is reached. Unless the file is in some useful order a serial search has to be used.
Students will revisit and discuss the theoretical computational methods and programming techniques covered in the previous year, as they have been applied to their NEA projects.
One of the 3 basic programming constructs. Instructions happening one after the other in order is sequence.
One of the 3 basic programming constructs. A selection of code which can be repeated either a set number of times (count controlled) or a variable number of times based on the evaluation of a Boolean expression (condition controlled) is iteration.
One of the 3 basic programming constructs. Instructions which can evaluate a Boolean expression and then branch the code to one or more alternatives paths is branching / selection.
An advanced programming construct in which a block of code (often a function) is able to call itself. Recursion algorithms must be designed carefully so that terminating condition will be met.
A variable which can be used anywhere in the program.
A variable which is defined and can only be used within one part of the program (normally a single function or procedure).
A technique of code design where a solution is broken down into a number of small self-contained and manageable chunks. Each Module of code should be designed to perform one set specific purpose. If during design it is found that the module starts to grow and performs more than one task then the additional functionality should be split out into a new module.
A block of code given a unique identifiable name within a program. A function can take either zero or more parameters when it is called and should return a value. The function should be designed and written to perform one task or action which is clearly indicated by its name.
A block of code given a unique identifiable name within a program. A procedure can take either zero or more parameters when it is called. The procedure should be designed and written to perform one task or action which is clearly indicated by its name.
Data structures passed into a Procedure or Function when they are initially called.
The process of providing a procedure, function or module with values at the point when you call it.
If a data item is passed by value, a (local) copy of the data is used, which is discarded when the subprogram exits.
If a data item is passed by reference, the location (in memory) of the data is used. This means that any changes are retained after the procedure or function has been completed.
Integrated Development Environment: Software that performs the various stages of software design and implementation in a single integrated system. It will usually include facilities for project management, design, graphical design, programming, testing and producing documentation.
The process of removing syntactical, semantic (logical) and run-time errors from computer code.
Describes any method which does something related to computation, such as sorting, merging, searching, indexing etc.
The acknowledgement and definition of an issue that does or may arise during the performance of a process.
The process by which a complex problem or system is broken down into parts that are easier to conceive, understand, program and maintain.
Another term for decomposition which is the process by which a complex problem or system are broken down into parts that are easier to conceive, understand, program and maintain.
An algorithm for finding a complete solution. This is a refined brute force methodology. It is a very general algorithm for finding all (or some) solutions to computational problems. It incrementally builds to the solution, and abandons each partial success (backtracks) as soon as it determines that the partial solution cannot possible be completed to a valid solution.
The analysis of a large amount of data in a data warehouse to provide new information. For example, by using loyalty cards, which connect purchases to a particular customer, supermarkets can gathering information about the buying habits of individual customers.
Rules that are not derived purely from logic but are derived from the experience (of a person). These are also known as rules of thumb.
This is the process of carrying out mathematical approximations of how well models perform. e.g. How efficient they are.
The process of turning data in a visual representation which is easier for humans to understand, interrupt and work with.
Students will understand how HTML, CSS and JavaScript are used to create web pages and how search engine indexing is implemented.
A table with no normalisation. All data and all fields in one table
First Normal Form: A relationship with repeating groups removed. That is a relation in which the intersection of each tuple and attribute contains one and only one value.
Second Normal Form: A relation that is in 1NF and every non-primary key attribute is fully dependant on the primary key. That is, all the incomplete dependencies have been removed
Third Normal Form: A relation that is in 1NF and 2NF, and in which no non-primary key attribute is transitively dependant on the primary key. That is, all non-key elements are fully dependant on the primary key
Atomicity, Consistency, Isolation, Durability: A set of properties that guarantee that database transactions are processed reliably. In the context of databases, a single logical operation on the data is called a transaction.
This method of encryption involves using a pair of keys to encrypt and decrypt a message so that it arrives securely. Initially, a network user receives a public and private key pair from a certificate authority.
A method of sending data over a wide area network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. All data then follows this same path for the duration of the data transfer.
Client-side processing refers to operations that are performed by the client in a client-server relationship in a computer network. Typically, a client is a computer application, such as a web browser, that runs on a users local computer and connects to a server as necessary.
A method of network organisation in which network stations make use of resources available at one or more servers.
When more than one field is added together to form a unique primary key for a table.
Cascading Style Sheets: A definition of the formatting and layout of elements of an HTML document. The stylesheet may be part of the HTML document, or stored as a separate file linked to the document. The use of different stylesheets linked to the same document allows appropriate layout of the same content on, for example, mobile devices, display screens.
A class of lossless data compression algorithms which operate by searching for matches between the text to be compressed and a set of strings contained in a data structure (called the dictionary) maintained by the encoder.
Domain Name System: The Internets equivalent of a phone book. They maintain a directory of domain names and translate them to Internet Protocol (IP) addresses. This is necessary because, although domain names are easy for people to remember, computers or machines access websites based on IP addresses.
The process of making data in a computer system unintelligible.
Entity Relationship Modelling: The process of producing a data model for describing the data or information aspects of a business domain or its process requirements, in an abstract way that lends itself to ultimately being implemented in a data such as a relation database.
A computer application used in a network to prevent external users gaining unauthorised access to a computer system.
A database that allows the user to specify data attributes (columns, databases etc.) for only one table at a time, storing those attributes independently
The linking field in the foreign table formed when a relationship is made. The FK becomes by default the PK of the new table.
The process of calculating a numeric value from one or more data items. While this value obviously depends on the value of the data items, it need not depend on the meaning attached to themn, simply producing a number that is used within the computer.
HyperText Markup Language: A mark-up language developed for multimedia documents, such as World Wide Web Pages.
The process of creating a database index, which is a data structure that improves the speed of data retrieval operations on a dataset table at the cost of additional writes and storage space to maintain the index data structure.
An object-oriented computer programming language commonly used to create interactive effects within web browsers.
Local Area Network: A collection of computers / computing devices on the same network which are physically close together, for example, all located within one building or site e.g. a home or school network.
A very simple form of data compression in which runs of data (that is, sequences in which the same data value occurs in many consecutive data elements) are stored as a single data value and count, rather than as the original run.
A compression scheme that allows the original images to be recreated.
A compression scheme where their generally involves a loss of resolution in parts of the image where experiences shows that it will be least noticed.
A way of structuring the data in a relational database according to formal rules, in order to avoid problems of efficiency and security in accessing and maintain the data.
The process of arranging data in tables and setting their relationships to move them through normal forms
A method of sending data over a wide area network in which the message is broken into a number of parts which are sent independently, over whatever route is optimum for each packet, and reassembled at the destination.
An algorithm used by Google Search to rank websites in their search engine results. It works by counting the number and quality of links to a page to determine a rough estimate of how important the website is. The underlying assumption is that more important websites are likely to receive more links from other websites.
A method of network organisation in which network stations can share resources on other network stations, so one station can use a printer on another station or save data on another stations local storage.
A field that uniquely identifies a record in a table
A set of rules that allow two devices to communicate.
The concept of a protocol not simply being a set of rules but those rules being built up into very specific layers and those rule layers behind built on top of each other in a deliberate order creating a layered protocol stack. This results in the rules of a protocol being executed in a specific sequence as you move through the protocol stack.
A computer application that accesses data on a different computer system or network. It controls the access of authorised users to data and allows the operation of the system to be isolated from control by external users.
A technique of preventing simultaneous access to data in a database, to prevent inconsistent results. The classic example is demonstrated by two bank clerks attempting to update the same bank account for two different transactions.
Redundancy occurs in database systems which have a field that is repeated in two or more tables For instance, when customer data is duplicated and attached with each product bought, then redundancy of data is a known source of inconsistency since customer might appear with different values for given attributes.
A measure of the consistency of the data in a database. It is violated when the relation to which a foreign key refers to no longer exists.
Allows the user to specify information about multiple tables and the relationship between those tables
The method of collecting, parsing and storing data to facilitate fast and accurate information retrieval.
A key field which can be used to access a table in a different way
Server-side processing refers to operations that are performed by the server in a client-server relationship in computer network. Typically, a server is a computer program, such as a web server, that runs on a remote server, reachable from a users local computer.
Structured Query Language: The language and syntax used to write and run database queries
The oldest and best-known encryption technique. A secret key, which can be a number, a word, or just a string of random letters, is applied to the text of a message to change the content in a particular way. This might be as simple as shifting each letter by a number of places in the alphabet.
Transmission Control Protocol / Internet Protocol: The most common general-purpose standard protocol that allows any networked computers (including those on The Internet) to communicate with each other whatever their equipment.
Information processing that is divided into individual, indivisible operations, called transactions. Each transaction must succeed or fail as a complete unit, it can never be only partially complete.
Wide Area Network: A collection of computers / computing devices on the same network which are spread out over a geographically large area, for example a university across several campuses, or a multinational corporation with offices / sites in different cities or even different countries.
In this topic, students will extend their understanding of logic gates and logic circuits, and be able to construct truth tables for a variety of circuits. Student will learn how to write Boolean expressions using a variety of notations and simplify them. Students will develop their understanding of logic and learn about the correspondence between a truth table and a Karnaugh map. Students will also understand the logic associated with D type flip flops and be able to recognise an trace the logic of half adders and full adders.
Used to store the logical conditions TRUE / FALSE. Often translated to On/Off, Yes/No etc.
Binary describes a numbering scheme in which there are only two possible values for each digit: 0 and 1. The term in computing refers to any digital encoding system in which there are exactly two possible states. E.g. in memory, storage, processing and communications, the 0 and 1 values are sometimes called low and high, respectively.
A logical operator used within a program. AND works by only returning TRUE if both values being compared are TRUE.
A logical operator used within a program. OR works by returning TRUE as long as either value being compared is TRUE.
A logical operator used within a program. XOR stands for exclusive OR. It will return TRUE if the two items being compared are different.
Named after the nineteenth-century mathematician George Boole, Boolean logic is a form of algebra in which all values are reduced to either TRUE or FALSE.
Also know as the K-Map, is a method to simplify Boolean algebra expressions. The Karnaugh map reduces the need for extensive calculations by taking advantage of humans pattern-recognition capability. They are used to simplify real-word logic requirements so that they can be implemented using a minimum number of physical logic gates.
A set of rules for manipulating truth values according to truth tables. Very important in computing as truth values in Boolean algebra are True and false, and can thus easily be represented as the binary digits 1 and 0.
Two laws in Boolean algebra which state that AND and OR, or union and intersections, are duel. The rules can be expressed in English as 1) The negation of a conjunction is the disjunction of the negations. 2) The negation of a disjunction is the conjunction of the negations. Or more informally as 1) "not (A and B)" is the same as "(not A) or (not B)" and also 2) "not (A or B)" is the same as "(not A) and (not B)". The purpose of De Morgans laws is to simplify the design of electronic circuits.
A rule or law in Boolean algebra which permits the multiplying or factoring out of an expression.
A rule or law in Boolean algebra which permits the removal of brackets from an expression and regrouping of the variables.
A rule or law in Boolean algebra which stats that the order of application of two separate terms is not important: A AND B = B AND A.
A rule or law in Boolean algebra where if you invert a term twice it is equal to its original term: (NOT NOT A) = A
A method of expression Boolean Logic in a diagrammatic form using a set of standard symbols representing the various Logic Gates such as AND NOT OR NAND etc.
A notation used in Boolean algebra for defining the output of a logic gate or logic circuit for all possible combinations of inputs.
Also known as a data or delay flip flop. This is a circuit or logic design which can be viewed as a memory cell. It has two stable states. Using appropriate input signals, you can trigger the flip-flop from one state to the other.
A unit which adds together two input variables. A half adder can only add the inputs together.
A unit which adds together two input variables. A full adder can a bit carried from another addition as well as the two inputs.
For this unit, students choose their own problem to solve. Students will be expected to analyse, design, develop, test, evaluate and document a program written in a suitable programming language. The underlying approach to the project is to apply the principles of computational thinking to a practical coding problem.
Learners are expected to apply appropriate principles from an agile development approach to the project development.
3.1 - Analysis of the problem (10 marks)
3.2 - Design of the solution (15 marks)
3.3 - Developing the solution (25 marks)
3.4 - Evaluation (20 marks)
Students will prepare for final examinations focusing on areas for development from the mock examination analysis. There are two 2 hour 30 minute examinations, each worth 40% of the overall qualification (80% in total).
This unit will explore how computers can be used to solve problems and programs can be written to solve them using the programming constructs of sequence, iteration and selection using both procedural/imperative and object oriented techniques. Students will learn the features that make a problem solvable by computational methods using decomposition and abstraction and apply their knowledge of backtracking, data mining, heuristics, performance modeling, pipelining and visualisation to solve problems.
One of the 3 basic programming constructs. Instructions happening one after the other in order is sequence.
One of the 3 basic programming constructs. A selection of code which can be repeated either a set number of times (count controlled) or a variable number of times based on the evaluation of a Boolean expression (condition controlled) is iteration.
One of the 3 basic programming constructs. Instructions which can evaluate a Boolean expression and then branch the code to one or more alternatives paths is branching / selection.
An advanced programming construct in which a block of code (often a function) is able to call itself. Recursion algorithms must be designed carefully so that terminating condition will be met.
A variable which can be used anywhere in the program.
A variable which is defined and can only be used within one part of the program (normally a single function or procedure).
A technique of code design where a solution is broken down into a number of small self-contained and manageable chunks. Each Module of code should be designed to perform one set specific purpose. If during design it is found that the module starts to grow and performs more than one task then the additional functionality should be split out into a new module.
A block of code given a unique identifiable name within a program. A function can take either zero or more parameters when it is called and should return a value. The function should be designed and written to perform one task or action which is clearly indicated by its name.
A block of code given a unique identifiable name within a program. A procedure can take either zero or more parameters when it is called. The procedure should be designed and written to perform one task or action which is clearly indicated by its name.
Data structures passed into a Procedure or Function when they are initially called.
The process of providing a procedure, function or module with values at the point when you call it.
If a data item is passed by value, a (local) copy of the data is used, which is discarded when the subprogram exits.
If a data item is passed by reference, the location (in memory) of the data is used. This means that any changes are retained after the procedure or function has been completed.
Integrated Development Environment: Software that performs the various stages of software design and implementation in a single integrated system. It will usually include facilities for project management, design, graphical design, programming, testing and producing documentation.
The process of removing syntactical, semantic (logical) and run-time errors from computer code.
Describes any method which does something related to computation, such as sorting, merging, searching, indexing etc.
The acknowledgement and definition of an issue that does or may arise during the performance of a process.
The process by which a complex problem or system is broken down into parts that are easier to conceive, understand, program and maintain.
Another term for decomposition which is the process by which a complex problem or system are broken down into parts that are easier to conceive, understand, program and maintain.
An algorithm for finding a complete solution. This is a refined brute force methodology. It is a very general algorithm for finding all (or some) solutions to computational problems. It incrementally builds to the solution, and abandons each partial success (backtracks) as soon as it determines that the partial solution cannot possible be completed to a valid solution.
The analysis of a large amount of data in a data warehouse to provide new information. For example, by using loyalty cards, which connect purchases to a particular customer, supermarkets can gathering information about the buying habits of individual customers.
Rules that are not derived purely from logic but are derived from the experience (of a person). These are also known as rules of thumb.
This is the process of carrying out mathematical approximations of how well models perform. e.g. How efficient they are.
The process of turning data in a visual representation which is easier for humans to understand, interrupt and work with.
Students will learn about key Acts relating to computer science and be able to discuss the challenges facing legislators especially due to the developments in technology. Students will learn about ethical and environmental issues arising from the use of digital technology, positive and negative impacts of the use of technology in society as well as be able to discuss some of the moral challenges which arise from the advancements in digital technology such as artificial intelligence and automated decision making.
The Data Protection Act 2018: Legislation which protects individuals from unreasonable use of their store personal data.
The Computer Misuse Act 1990: Legislation which defines electronic vandalism, unauthorised access to computer systems and theft of information.
The Copyright Design and Patents Act 1988: Legislation which gives creators of literacy, dramatic, musical and artistic works the right to control the ways in which their material may be used.
The Regulation of Investigatory Powers Act 2000: Legislation which regulates the powers of public bodies to carry out surveillance and investigation, and covering interception of communications.
In this unit, students will learn about the theory of algorithms such as searching and sorting algorithms (bubble sort, insertion sort, merge sort, quick sort), with reference to Big-O notation in terms of time and space complexity. Students will investigate standard algorithms for depth-first and breadth-first graph traversals. Optimisation algorithms, such as Dijkstra’s shortest path algorithm and the A* algorithm are also covered along with a discussion of intractable problems.
A sequence of steps designed to perform a particular task. An algorithm may be constructed to describe the operation of a complete system or to describe a particular part of it.
Used in computer science to describe the performance or complexity of an algorithm. Big-O specifically described the worst-case scenario, and can be used to describe the execution time required or the space used (e.g. in memory or on disk) by an algorithm.
A simple algorithm popular with inexperienced programmers. It is inefficient when sorting large amounts of data as the time taken is related to the square of the number of items. If 10 items take 1ms then 100 times will take 100ms (this is 10 times the number of items and so the time will be 102 or 100 times longer).
A simple sorting algorithm that builds the final sorted array (or list) one item at time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort.
A type of divide and conquer algorithm that was incited by John von Neumann. First the list is divided into the smallest unit (1 element), then each element is compared with the adjacent list to sort and merge the two adjacent lists. Finally all elements are sorted and merged.
A type of divide and conquer algorithm which sorts the given sequence in place meaning that it doesnt require extra storage as would be needed in a merge sort. The basic idea is dividing the sequence into two sub-lists around an element which is called the pivot such that all elements in the lower sub-list are less than the value of the pivot element and all elements in the higher sub-list are greater than the pivot element.
A graph search algorithm that solves the single-source shortest path problem for a graph with non-negative edge path costs, producing a shortest path tree. This algorithm is often used in routing and as a subroutine in other graph algorithms. In practice in picks an unvisited vertex with the lowest-distance, calculates the distance through it to each unvisited neighbour, and updates the neighbours distance if smaller. It the marks the visited when done with neighbours.
Widely used in pathfinding and graph traversal, the process of plotting an efficiently traversable path between points, called nodes. A* uses a best-first search and finds a least-cost path from a given initial node to one goal node (out of one or more possible goals). As A* traverses the graph, it follows a path of the lowest expected total cost or distance, keeping a sorted priority queue of alternate path segments along the way.
A particularly efficient search method. It only works if records in the file are in sequence. A binary search involvers accessing the middle record in the file and determining if the target record has been found or, if not, if it is before or after in the sequence. This process is repeated on the part of the file where the target record is expected, until it is found.
Involves examining each entry in turn in the file until the time is found or the end of the file is reached. Unless the file is in some useful order a serial search has to be used.
For this unit, students choose their own problem to solve. Students will be expected to analyse, design, develop, test, evaluate and document a program written in a suitable programming language. The underlying approach to the project is to apply the principles of computational thinking to a practical coding problem.
Learners are expected to apply appropriate principles from an agile development approach to the project development.
20% of the qualification. Internally assessed.
3.1 - Analysis of the problem (10 marks)
3.2 - Design of the solution (15 marks)
3.3 - Developing the solution (25 marks)
3.4 - Evaluation (20 marks)