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Learn what a tag is in HTML and which ones are necessary to format a webpage ready for text and other content. 2. Creating Essential Tags HTML Guide Watch on YouTube: What is a tag ? HTML uses tags to define the content of a webpage . A tag uses angle brackets - they look just like my teeth... Some examples of tags are and and Most tags have a start tag and an end tag . The actual content is written in between the tags . For example : The p tag is used to write a paragraph Notice that the end tag uses a forward slash . < > Essential Tags There are three tags that are essential for every HTML web page : - This tag declares the start and the end of your html web page. - The head is the part of the web page that the user will not see. - The body holds all of the content of the web page (text, images, video etc.) Don't forget to use backslash for the end tags : / Use the image on the right to add the three essential tags (and their end tags) to your document. Now it is time to add something we can actually see! Text tags are up next. 1. Setup HTML Guide 3. Text Tags

Learn about the differences between wired and wireless networks. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 3.2a: Wired & Wireless Networks Exam Board: OCR Specification: J277 Watch on YouTube : Wired Networks Wireless Networks Encryption Wired Connections Wireless Connections Wireless connections, such as WiFi or Bluetooth , use no cables but require a wireless network interface card (WNIC ). Wireless connections generally have a slower speed and can be affected by the computer's distance from the wireless router as well as obstacles like walls or bad weather. Wired connections use physical cables , such as copper or fibre optic wires , and require a network interface card (NIC ) to connect to a network. These wired connections use a wired connection protocol - most commonly Ethernet . Restricted Movement Faster More Secure NIC Required Freedom of Movement Slower Less Secure WNIC Required Encryption Wireless connections are less secure and require encryption . Encryption is the process of scrambling data into an unreadable format so that attackers cannot understand it if intercepted during transmission. The original data (known as plaintext ) is converted to scrambled ciphertext using an encryption key . Only at the correct destination will the encryption key be used to convert the ciphertext back into plaintext to be understood by the receiving computer. Q uesto's Q uestions 3.2a - Wired & Wireless Networks: 1. Briefly compare wired and wireless networks in terms of movement , transmission speed , security and required hardware . You could answer this in the form of a table. [ 8 ] 3.1b - Network Hardware & Internet Theory Topics 3.2b - Protocols & Layers

Learn how to make simple calculations in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 3b - Simple Calculations Simple Calculations in Python You can perform calculations on numbers in Python using the four main operators : print ( 89 + 47) print ( 89 - 47) print ( 89 * 47) print ( 89 / 47) = 136 42 4183 1.8936170212765957 For addition , use the plus sign + To subtract numbers, use the dash symbol – (but not an underscore _ ) For multiplication , use an asterisk * which can be made by pressing Shift and 8 on a typical keyboard. To divide numbers, use a forward slash / (but not a backslash \ ) Use a string and the calculation to make the output user friendly . print ( "53 x 7 =" , 53 * 7) = 53 x 7 = 371 Simple Calculations Task 1 ( + - * /) Print four different simple calculations, using a different operator ( + - * / ) for each. Make the output user friendly by also showing the calculation (not just the answer). Copy the divide symbol here using Ctrl and C : ÷ Example solution: 18 + 35 = 53 18 - 35 = -17 18 x 35 = 630 18 ÷ 35 = 0.5142857142857142 Using Variables in Calculations You can also perform calculations on variables . The example below has the values of the variables pre-written. You need to store the result in a variable . The total variable has been used to store the result of the multiplication. num1 = 12 num2 = 20 total = num1 * num2 print ( "The total is" , total) = The total is 240 The example below allows the user to input values . num1 = int ( input ( "Enter number one: " )) num2 = int ( input ( "Enter number two: " )) total = num1 + num2 print ( "The to ta l is" , total) Enter number one: 21 Enter number two: 82 The total is 103 = Don't leave the user in the dark, better user interfaces are clear and explain what outputted values mean: num1 = int ( input ( "Enter number one: " )) num2 = int ( input ( "Enter number two: " )) answer = nu m1 - num2 print (num1 , "-" , n um2 , "=" , answer) Enter number one: 83 Enter number two: 29 83 - 29 = 54 = Simple Calculations Task 2 ( Divide by 3) Use an input line with int to ask the user to enter a number . Divide the number by 3 and output the result . Example solution: Enter a number: 11 11 divided by 3 is 3.6666666666666665 Simple Calculations Task 3 ( Add 3 Numbers ) Make three input lines using int to ask the user to enter three numbers . Add the numbers together and output the total . Example solution: Enter the first number: 45 Enter the second number: 32 Enter the third number: 19 The total is 96 ⬅ 3a - Data Types Section 3 Practice Tasks ➡

Learn how to read and search through files in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. Python 10b - Read & Search Files Reading from a File To read and print from a file you must open it in read mode by typing "r" instead of "a". If you are writing and reading in the same program, make sure you close the file in append mode before you open it in read mode . The program below uses the Customers.txt file from the last section. A simple for loop can be used to print each line of the file. The end = "" code just prevents a space between each line. Practice Task 1 Open one of the files that you used in Section 10a and print each line. Example solution: Reading Specific Lines from a File Sometimes it is necessary only to print certain lines. The following example uses a file where I have written a sentence of advice on each line. The user is asked to enter a number between 1 and 6. If they enter 1, the first line of the file is printed. If they enter 2, the second line of the file is printed etc. Remember Python starts counting everything at 0 so each line is a digit less than you would expect . Square brackets must be used to denote the line to print: [1] not (1). The end = "" code is not necessary but removes space after the line. Practice Task 2 Create a text file (saved in the same folder as your Python file) with a list of video games. Ask the user to enter a number between 1 and 10. Print the line for the number that they input. Example solution: Print a Random Line The randint command can be imported and used to print a random line from a file . The example below prints one of the 12 months . The file is opened in read mode and the readlines() command extracts each line , placing them in a list . A random number is then generated between 0 and one less than the total number of lines . This random number is then used to print a line from the extracted list of lines . Python code from random import randint file = open ( "months.txt" , "r" ) lines = file.readlines() random = randint(0,11) print (lines[random]) months.txt January February March April May June July August September October November December potential outputs March December April July If the length of the file is not fixed (e.g. new lines are being added or lines removed ) then the random number generation line can be adapted to use the len command to calculate the current number of lines . This is required to know the upper limit of the random number . random = randint(0,len(lines)-1) Searching Through Files A for loop is used to search through a file , line by line . First, an input line is used to allow the user to enter their search term . If the term that is being searched for is found, then the whole line is printed. The example below uses a variable named found to state if there is a match when the file is searched. If the search term is found, then the found variable is changed to true . If the search term is not found , the found variable remains as false, so the 'no customers found' statement is printed . Practice Task 3 You should have completed Practice Task 2 from Section 10a (the A Level task). Add extra code to that program so that you can search for specific students. Example solution: ⬅ 10a - Open & Write Files 10c - Remove & Edit Lines ➡

Learn about the tags that improve the layout of a web page, including how to centre content and add horizontal lines, bullet points and block quotes. 6. Organisation HTML Guide Watch on YouTube: This page explains the following tags which can be used to structure a simple page layout: Horizontal Line Centre Quote Bullet Points Numbered Points hr Horizontal Line You can add a horizontal line by simply adding to your document. There is no close tag. Add at least one horizontal line to your web page. center Centre Align This tag places the content within the tags on the centre of the page . Be careful - you need to use the American spelling - 'center ' - in your tags. Add tags to place your main heading in the centre of the page. blockquote Blockquote A blockquote is used to display a quote from another person or place. Text is indented further from the margin than the other content. It is not used very often, but can be found in some online articles and essays. Add at least one block quote to your web page. uo list Unordered List An unordered list is a set of bullet points . The tag is placed before the bullet points and afterwards. Each bullet point is placed within tags. That stands for list item . Add either an unordered or ordered list to your web page. Include at least three items in your list. o list Ordered List An ordered list will number each line . The tag is placed before the list and afterwards. Each list item is placed within tags. Add either an unordered or ordered list to your web page. Include at least three items in your list. Next it is time to add tags to the head, including a page title and metadata. 5. Images HTML Guide 7. Head Tags

The list of topics in the 2020 OCR GCSE Computer Science specifications. OCR GCSE Computer Science (J277) These pages are based on the J277 OCR GCSE Computer Science specification . This website is in no way affiliated with OCR . Component One: Computer Systems OCR GCSE Key Term Generator Paper 1 Playlist on YouTube 1. Systems Architecture 1.1a - The CPU 1.1b - Registers & FE Cycle 1.2 - CPU Performance 1.3 - Embedded Systems 2. Memory & Storage 2.1 - Primary Storage 2.2 - Secondary Storage 2.3 - Units 2.4a - Number Systems 2.4b - Binary Addition & Shifts 2.4c - Character Storage 2.4d - Image Storage 2.4e - Sound Storage 2.5 - Compression 3. Networks 3.1a - Network Types & Performance 3.1b - Network Hardware & Internet 3.2a - Wired & Wireless networks 3.2b - Protocols & Layers 4. Network Security 4.1 - Network Threats 4.2 - Preventing Vulnerabilities 5. Systems Software 5.1 - Operating Systems 5.2 - Utility Software 6. Impacts 6.1a - Impacts of Technology 6.1b - Legislation Component Two: Computational Thinking, Algorithms and Programming Paper 2 Playlist on YouTube 1. Algorithms 1.1 - Computational Thinking 1.2 - Designing Algorithms 1.3 - Searching & Sorting Algorithms 2. Programming Fundamentals 2.1 - Programming Fundamentals 2.2 - Data Types 2.3 - Additional Programming Techniques 3. Producing Robust Programs 3.1 - Defensive Design 3.2 - Testing 4. Boolean Logic 4.1 - Boolean Logic 5. Languages & IDEs 5.1 - Languages & Translators 5.2 - Integrated Development Environment

Learn how to input strings (text) in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 2a - Inputting Text Inputting Text (Strings) in Python A string is a collection of characters (letters, numbers and punctuation) such as: “Wednesday” , “Toy Story 4” or “Boeing 747” . Use the input command to ask a question and let a user input data , which is automatically stored as a string . Variable to save the answer into. Give it a suitable name based on the input. name = input ( "What is your name? " ) = What is your name? Paulina Type your answer directly into the editor and press the Enter key. Statement that is printed to the screen. Leave a space to make the output look clearer. Once an input has been saved into a variable, it can be used for other purposes, such as printing it within a sentence : name = input ( "What is your name? " ) print ( "It is nice to meet you" , name) = What is your name? Jake the Dog It is nice to meet you Jake the Dog Always choose an appropriate variable name when using inputs. colour = input ( "What is your favourite colour? " ) print ( "Your favourite colour is " + colour + "? Mine is yellow." ) = What is your favourite colour? blue Your favourite colour is blue? Mine is yellow. Inputting Text Task 1 ( Holiday) Write an input line to ask the user where they last went on holiday . Write a print line that uses the holiday variable (their answer). Example solution: Where did you last go on holiday? Scotland I hope you had a nice time in Scotland Inputting Text Task 2 ( New Neighbour) Write an input line to ask the user for a title (e.g. Mr, Mrs, Dr). Write another input line for an object . Write a print line that uses both input variables (title and object ). Example solutions: Enter a title: Dr Enter an object: Fridge I think my new neighbour is Dr Fridge Enter a title: Mrs Enter an object: Armchair I think my new neighbour is Mrs Armchair Using a Variable Within an Input To use a variable you have previously assigned a value t o within the input statement you must use + (commas will not work). drink = input ( "What would you like to drink? " ) option = input ( "What would you like with your " + drink + "? " ) print ( "Getting your" , drink , "and" , option , "now...." ) = What would you like to drink? tea What would you like with your tea? biscuits Getting your tea and biscuits now... What would you like to drink? apple juice What would you like with your apple juice? cake Getting your apple juice and cake now... Inputting Text Task 3 ( Name & Game) Ask the user what their name is. Ask the user what their favourite game is. Use their name in the input statement for their game. Print a response with their name and the game they entered. Example solutions: What is your name? Rory Hi Rory, what's your favourite game? Minecraft Rory likes Minecraft? That's nice to know. What is your name? Kayleigh Hi Kayleigh, what's your favourite game? Stardew Valley Kayleigh likes Stardew Valley? That's nice to know. ⬅ Section 1 Practice Ta sks 2b - I nputting Numbers ➡

A simple HTML and CSS editor using Code Minrror libraries. Learn how to create simple web pages using HTML. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. Simple HTML & CSS Editor This page is under active development.

Learn how to edit code in Greenfoot to make objects move randomly across the screen. This can be used on 'enemy' objects. Part 3 of the Greenfoot Tutorial for the Eduqas / WJEC GCSE 2016 specification. 3. Random Movement 1. Code for Random Movement Greenfoot Tutorial Watch on YouTube: Right-click on your enemy class on the main screen and select ' Open editor '. The enemy character should always be moving, so start with move(1); Next we will use an if statement to start the random movement. This code generates 10 random numbers and if it is less than 1 then it will run the proceeding code. If we don't do this, the character will turn too much or too little . This code generates a random angle between 0 and 90. The - 45 part is necessary otherwise the character will always move to the right . See the diagram below for an explanation: 2. Bounce at World Edge You may have noticed that the enemy objects can get 'stuck' in the corners or when they hit the edge of the world. In the act() method, below the random movement code , add the code in the red box . This code checks to see if the object is at the edge , and turns it around ( 180 degrees ) if it is. 3. Compile and Run Click the Compile button at the top of the code editor . Then you can go back to the main Greenfoot window and click Run to test if your enemy objects move . Click on me if you've got an error that you're stuck with. < Part 2 - Movement with the Arrow Keys Part 4 - Remove Objects >

Learn how to use App Inventor 2 to create simple programs. Try to complete tasks 4, 5 and 6 on this page. Perfect for Key Stage 3 students to experiment with block coding, objects and properties. App Inventor Tasks 4, 5 & 6 - Using Variables This page will teach you how to make three simple apps that use variables . These apps will prepare you for the final program - the Pop-up Blob game. App #4 - Button Masher The first app to make is a simple program that counts how many times a button is pressed (but don't press it too much! ) This app will introduce you to using variables in App Inventor. Open App Inventor 2 (use the button below) and create a new project. You will need to log in with a Google account. App Inventor 2 Firstly, grab a button and two labels and place them in the Viewer . Using the Properties tab, you need to make the following changes: Button Text to 'Press Me!' Button Height to 60 pixels and Width to 'Fill parent...' Label 1 Text to 'Number of Presses' Label 2 Text to '0' Both Label 1 and Label 2 Width to 'Fill parent...' Both Label 1 and Label 2 TextAlignment to 'centre : 1' In the Components tab change the component names to be easier to code later. Switch to Blocks layout and drag an initialize global to block into the centre. In the blank space type 'Presses' - this is the name of the variable that will store how many times the button has been pressed. Drag a 0 block from Math. This will set the number of presses to 0 when the app starts. Drag a when ButtonPresses Clicked from the ButtonPresses section and add the necessary code inside. This code increases the variable value of Presses by 1 every time the button is clicked. It also changes the LabelPresses text to display the number of presses. Improve Your App As you will have seen in the video at the top, I programmed the app to go a bit crazy when 35 presses were recorded. In the code below I have shown how to use an if then block to check if the number of presses is 35. If it is then I have made the button invisible - this is an important feature we will use in later programs. Copy this code and add the following features to the then part of the if statement: Set the background colour to black. Change the Label1 Text Colour to white. Change the Label1 Text Size to 40. Change the Label1 Text to 'You broke it...' Program 4 Complete! App #5 - Timer The second app to make is a timer that counts up one second at a time. It also needs a reset button that sets the timer back to 0 again. It will introduce you to the clock component and enabling / disabling components. Open App Inventor 2 (use the button below) and create a new project. You will need to log in with a Google account. App Inventor 2 The code for this program is straightforward; it will take more effort getting the layout right. In the Palette tab, drag a HorizontalArrangement from the Layout section. It will look like an empty grey box at first. Grab a Button as well and place it underneath. Now drag two labels into the grey box and place the second one directly after the first, it may take a few attempts to get them to appear side by side like below: The last component to drag over is Clock (it is in the Sensors section in the Palette tab). It will go into its own section underneath: Change the name of some of the components so that they make more sense. Now to make some changes in the Properties tab. You should know enough by now to work out how to change your components so that it looks like this in your Viewer : Change your layout to Blocks and add the code blocks to the right. This code makes the Label named Seconds update by 1 every second, just like a timer. The code to the left will make the Label named Seconds reset to 0 when the button is pressed. Improve Your App As you will have seen in the video at the top of this task, I added a pause/unpause button that will set the enabled feature of the timer to true or false. You will need to complete the following steps (I've been deliberately vague to make it a challenge - break it down into small steps and use the colours to help you): Add a new button. Add code that, when the new button is clicked , checks if the TimerEnabled is true . If it is, then change TimerEnabled to false . Else change it to true . Now you also need to change the Text of the Button to read either "Pause" or "Unpause" . Program 5 Complete! App #6 - Windy Day The third app to make is an app that blows leaves around your screen. It will introduce you to random numbers, the canvas and coordinates . Open App Inventor 2 (use the button below) and create a new project. You will need to log in with a Google account. App Inventor 2 In the Palette tab, drag a Canvas from the Drawing and Animation section. A Canvas allows sprites (objects) to move around inside of it. In Properties , change the Height and Width of Canvas to 'Fill parent...' for both, so it fills the whole screen. In the Palette tab, drag over five ImageSprites from the Drawing and Animation section and drop them anywhere inside the canvas. Download the leaf picture with all App Inventor images on the basics page here . Upload the leaf image it in the Media tab. In the Components tab change the names of your ImageSprites to be leaf1, leaf 2 etc. For each leaf sprite, in the Properties tab, change the Picture to the leaf you just uploaded and change Height and Width to 30 pixels each. Finally, in the Palette tab, in the Sensors section, drag over a Clock . Your Viewer should look like the image to the left. X axis Y axis 0 300 500 Now for an explanation of coordinates. Each sprite (leaf) has an x coordinate (horizontal) and a y coordinate (vertical). For example, the leaf in the top right would have coordinates of x = 270 and y = 100. Can you work out approximately what the other leaves coordinates would be? What the code blocks below do is randomise the x and y coordinates for leaf1 every second. The word integer means a whole number . Use this code and add to it to make all 5 leaves randomly change coordinates. Improve Your App Add a pause / unpause button, just like in the Timer app that pauses the timer so that the leaves stop blowing (and starts them blowing around again too). Find a nice picture (maybe of a park?) online and upload it in the Media tab. Set this as the Canvas BackgroundImage . Add an audio file of some whooshing (why not record it yourself?). Program 6 Complete! Task 7 KS3 Home

Learn about different data structures such as arrays, lists and records. Also, the difference between static and dynamic data structures and how to design files. Based on the 2020 Eduqas (WJEC) GCSE specification. 5.1: Data Structures & File Design Exam Board: Eduqas Specification: 2020 What is a Data Structure? A data structure is a way of efficiently organising data . There are two general forms of data structures: Static Data Structures The size of a static data structure cannot change e.g. if a data structure has 20 elements, no additional elements can be added or removed. The values of the data elements can be changed, but memory size is fixed when allocated at compile time. Because a static data structure holds a certain number of data elements they are easier to program because the size of the structure and the number of elements never change. An array is an example of a static data structure. Examples: A static data structure could be an array of teams in the Premier League. The data elements will change each year when teams are relegated and promoted but there will always be 20 teams. Dynamic Data Structures The size of a dynamic data structure can change as the program is being run , it is possible to add or remove data elements. Dynamic data structures make the most efficient use of memory but are more difficult to program , as you have to check the size of the data structure and the location of the data items each time you use the data. A list is an example of a dynamic data structure. A dynamic data structure could be a list of all teams in the Premier League that won their last match. Data elements (teams) will be added or removed across the season. Types of Data Structures List A list is a dynamic data structure that has the data elements stored in the order they were originally added to memory . Every data structure starts at 0, not 1 . Lists store data elements in the order they were added, so the first doctor is 0 and the most recent doctor is 12. An example list of the main Doctor Who actors Array An array is a static data structure that can hold a fixed number of data elements . Each data element must be of the same data type i.e. real, integer, string. The elements in an array are identified by a number that indicates their position in the array. This number is known as the index. The first element in an array always has an index of 0 . You should know how to write pseudo code that manipulates arrays to traverse, add, remove and search data. The following steps uses Python as an example. Traversing an Array To traverse (' move through ') an array a for loop can be used to display each data element in order. 'Inserting' a value In an array the size is fixed so you cannot insert new values, but you can change the value of elements that already exist. Overwriting the fourth element (Daphne) with a new value (Laura) will change it from Daphne to Laura. Example code for traversing: Example code for inserting: Output: Output: 'Deleting' a value In an array the size is fixed so you cannot delete values, but you can overwrite them as blank . Overwriting the second element (Shaggy) with a blank space makes it appear deleted. Example code for deleting: Output: Searching an Array Example code for searching: For large arrays a for loop is needed to search through each element for a specific value . This example checks each name to see if it is equal to Velma. Output: Two-Dimensional Array Often the data we want to process comes in the form of a table . The data in a two dimensional array must still all be of the same data type , but can have multiple rows and columns . The two-dimensional array to the right shows the characters from Scooby Doo along with their associated colour and their species. Each value in the array is represented by an index still, but now the index has two values . For example [3] [0] is 'Daphne'. We measure row first , then column . Searching a two-dimensional array: To print a specific data element you can just use the index number like Daphne above. To search for a specific value you will need two for loops, one for the row and another for the values of each row. The example to the right is looking for the value of 'Velma' and when it is round it prints the associated data from the whole row. Example code for printing: Output: Example code for searching: Output: Records Unlike arrays, records can store data of different data types . Each record is made up of information about one person or thing. Each piece of information in the record is called a field (each row name). Records should have a key field - this is unique data that identifies each record . For example Student ID is a good key field for a record on students as no two students can have the same Student ID. Data files are made up of records with the same structure. It would be most efficient for the fields in a record to be stored next to each other so that the data can be read into the record data structure in memory for processing by the CPU. In an exam you may be asked to state and design a data structure for a given scenario. If the data structure can hold values of the same data type you should draw an array , usually a 2D array for multiple rows and columns. Remember that a record is required to store values of different data types . Example questions: "A video gamer has recorded their three lap times in four Mario Kart courses." " State and design the most suitable data structure for this data." A two-dimensional array is most suitable because only one data type ( real ) is stored. "A vet surgery stores data on all dogs and cats including the animal's name, age (in years), weight (in kg) and whether or not it has been vaccinated." " State and design the most suitable data structure for this data for four animals ." A record is most suitable because the data structure requires different data types . Q uesto's Q uestions 5.1 - Data Structures: 1. Give two differences between static and dynamic data structures . [ 4 ] 2. Describe the differences between a list , array and record . [ 3 ] 3. A one-dimensional array looks like this: TigerBreeds("Sumatran","Indian","Malayan,"Amur") Write the code to: a. Print the element with the index of 3. [ 2 ] b. Change Indian to South China. [ 2 ] c. Remove the Amur element. [ 2 ] d. Search through the array for 'Malayan'. [ 2 ] 4. State and design the most suitable data structure for these scenarios: a. For each book in a bookshop, the staff need to record the title, author, number of pages and whether or not it is a signed copy. Include data for three books. [ 3 ] b. Four dieters are recording how many kilograms they have lost each month for 5 months. [ 4 ] 5. Design a file that stores the first initial, surname, age and hair colour of each member of a family. [ 8 ] Designing Data Structures Data is stored in files when it needs to be kept after the program has stopped running . To learn how to write code for file handling (e.g. opening, writing to, reading from and closing files) in Python click here . Designing a file requires more than just the field name (e.g. Name) and data values (e.g. Rebecca). The data type (e.g. string) and any validation checks (e.g. format check) should also be considered. Below is an example file design for a bakery. Designing Files 4.8 Compression Theory Topics 6.1 - Operating Systems

Learn about programming constructs such as sequence, iteration and branching, recursion, local and global variables, modularity, functions and procedures, parameter passing by value and by reference, Integrated Development Environment (IDE) tools and object-oriented techniques. Based on the OCR H446 Computer Science A-Level specification. Exam Board: OCR A-Level Specification: Computer Science H446 2.1 - Programming Techniques Watch on YouTube : Programming constructs Recursion Local & global variables Modularity Integrated development environment Object-oriented programming Programming Constructs Sequence , iteration and branching (also called selection ) are the three fundamental programming constructs used to build algorithms . Sequence means that instructions run in a specific order , one after another. Iteration is the repetition of a set of instructions , usually being count-controlled , such as for loops , or condition-controlled , such as while loops or do until loops . Branching (selection ) allows a program to choose between different actions based on a condition , using structures like if , elif , else or switch . YouTube video uploading soon Recursion Recursion is where a function calls itself to solve a problem by breaking it down into smaller , simpler versions of the same problem . Recursion is often used for tasks that naturally fit a 'divide and conquer ' structure , such as quicksort and merge sort algorithms. It is also used for depth-first tree traversals and solving mathematical problems like factorials or the Fibonacci sequence . Compared to iteration , recursion can produce clearer and more elegant solutions , but it may use more memory and can be less efficient if the recursion goes too deep or lacks a proper base case (stopping condition ) , potentially running out of memory . YouTube video uploading soon Local & Global Variables Local variables are created inside a function or block and can only be accessed there , which makes programs safer and easier to debug because changes to the variable cannot affect other parts of the program ; however, they cannot store values that need to be shared across multiple functions . Global variables are declared outside all functions and can be accessed anywhere in the program , making them useful for storing information that many parts of the program need , but they can lead to errors if different functions accidentally change them and can make the program harder to maintain . YouTube video uploading soon Modularity Modularity is the practice of breaking a program into smaller , self-contained parts so each section can be developed , tested and understood independently . Functions and procedures are modular units of code: a function returns a value , while a procedure performs a task without returning a value . When data is passed into a subroutine , it can be passed by value , where a copy of the data is sent so the original cannot be changed , or passed by reference , where the subroutine receives direct access to the original data , allowing it to be modified . YouTube video uploading soon Integrated Development Environment An Integrated Development Environment (IDE ) is software that provides the tools a programmer needs to write , test and debug code in one place . It typically includes an editor for writing and formatting code , syntax highlighting to make keywords and errors easier to spot , and auto-completion to speed up coding . For debugging , an IDE often provides error diagnostics that highlight mistakes , a run-time environment to execute the program , and tools like breakpoints and step-through execution that allow the programmer to pause the program and inspect variables to find and fix bugs more easily . YouTube video uploading soon Object-Oriented Programming Object-oriented techniques are a way of designing programs by modelling them as collections of objects , each representing something with its own data and behaviours . These objects are created from classes , which act like blueprints describing the attributes (data ) and methods (actions ) an object will have . It uses key principles such as encapsulation (keeping an object’s data and methods together and protected ), inheritance (allowing classes to share and reuse features ) and polymorphism (enabling objects to behave differently ). These techniques make large programs easier to organise , maintain and extend by encouraging reusable , modular and well-structured code . YouTube video uploading soon This page is under active development. Check here for the latest progress update. Q uesto's K ey T erms Programming Constructs: sequence, iteration, selection (branching), if / elif / else, select (switch) case Recursion & Iteration: count-controlled loop, condition-controlled loop, recursion, base case Variables: local variable, global variable Modularity: function, procedure, parameter, pass by value, pass by reference Integrated Development Environment (IDE) Object Oriented Programming (OOP): class, object, method, attribute, inheritance, encapsulation, polymorphism D id Y ou K now? Roblox Studio is a free IDE for making Roblox games using the programming language Lua . With over 70m daily Roblox players , games built in Roblox Studio can reach a larger audience than many mainstream game engines . 1.1 - Computational Thinking A-Level Topics 2.2 - Computational Methods