France Seconde Digital Science and Technology
Chapters: 2
1. Themes
The Internet: IP, DNS, routing · The Web: HTML, HTTP, search engines · Social networks: graphs, business models, cyberbullying · Structured data: tables, CSV, metadata · Geolocation, digital maps · Embedded systems and connected objects · Digital photography
- Computer Networks and How the Internet Works – A network is a group of devices linked to share data. Each device has an IP address. Data is cut into numbered packets. Routers pass each packet hop by hop towards its address, and TCP puts the packets back in order. DNS turns a website name into an IP address. Clients ask, servers answer. Firewalls, passwords, updates and encryption keep a network safe.
- How Networks Grew and How Data Travels – A computer network is a group of connected devices that share data. Networking began with ARPANET (1969), grew into NSFNET (1980s) for universities, and joined with other networks to become the Internet, a network of networks. Every data communication has five parts: sender, receiver, message, communication media and protocol. Bandwidth is the range of frequencies a channel can carry (in Hz); data rate is how many bits travel per second (bps). Every device on a network has an IP address. Data can move by circuit switching (a fixed path is booked first) or packet switching (data is cut into packets that travel on their own).
- Web Services: What Happens When You Open a Website – The World Wide Web (WWW) is a system of linked web pages that live on the Internet and are reached with a browser. Web pages are written in HTML, which uses fixed tags to show content; XML uses tags you make yourself to store and carry data. Every website has a domain name, like example.org, which DNS turns into an IP address. A URL is the full address of one resource: protocol, domain and path. A website is a set of related web pages. A web browser asks for pages and shows them; a web server stores them and sends them; web hosting is renting space on such a server so your site is online all the time.
- Social Media and Social Networks – A social network is a graph: people are dots (nodes) and friendships are lines (edges). The number of friends of a person is the degree. Networks are "small worlds": any two people are linked by a short chain of friends. Most apps are free because advertisers pay for your attention and data. Online cruelty (cyberbullying) spreads fast on the same links, so block, report and tell an adult.
- Database Concepts: DBMS, Relations and Keys – Keeping data in separate files causes duplication, inconsistency and poor security. A database stores related data in one organised place, and a DBMS (like MySQL) is the software that manages it. In the relational model, data is kept in tables (relations) made of columns (attributes) and rows (tuples); a domain is the set of allowed values of a column. A candidate key uniquely identifies each row; one is chosen as the primary key and the others are alternate keys.
- Sensors: How Machines Sense the World – A sensor turns a physical quantity (light, temperature, distance, moisture, sound, pressure) into an electrical signal. Analogue sensors give a smooth voltage; an ADC turns it into a number the computer can use. A controller compares the number with a threshold and switches an actuator, often through a relay. Readings taken at regular times are data logging. Good sensors have the right range, sensitivity, accuracy and response time.
- Digital Media: How Pictures, Sound and Video Become Numbers – Digital media is any picture, sound, video or animation stored as numbers on a computer. A raster image is a grid of pixels, each stored as red, green and blue values from 0 to 255. Vector graphics store shapes as maths, so they stay sharp at any size. Video and animation are many frames shown quickly. File size grows with resolution and colour depth, so we use compression. When we make or share media we must respect copyright, licences and people's image rights, and work safely and critically.
2. Programming basics
Python: variables, conditions, loops, functions
- Python Basics: Modes, Variables, Data Types and Operators – Python runs in interactive mode (one line at a time) or script mode (a saved .py file). Blocks are shown by indentation. Variables are names tied to values; every value has a data type, and some types are mutable. Operators build expressions that Python works out by precedence. input() reads text, int()/float()/str() convert types, and debugging fixes syntax, runtime and logical errors.
- Getting Started with Python – Python is a high-level, free and open-source, interpreted, portable, case-sensitive language that is easy to read. You can run it in interactive mode (type after the >>> prompt and see the result at once) or script mode (save code in a .py file and run it). Python's character set includes letters, digits, special symbols, whitespace and all Unicode characters. The smallest units of a program are tokens: keywords, identifiers, literals, operators and punctuators. A variable is a name that refers to a value; in an assignment the right side (r-value) is evaluated first and stored in the left side (l-value). Comments start with # and are ignored by Python.
- Python Revision for Class 12: Everything from Class 11 in One Place – Class 12 builds on Class 11 Python. You must know tokens (keywords, identifiers, literals, operators, punctuators), data types (int, float, bool, str, list, tuple, dict), which types are mutable (can change in place) and which are immutable, operator precedence, if-elif-else, for and while loops with break and continue, string slicing, and the main methods of lists, tuples and dictionaries.