# LightMySky > 1,690 topics ordered by prerequisites. LightMySky tracks what a learner knows and brings a topic back before it is forgotten. 3,344 topics across 16 subjects, ordered by prerequisites. Each has a plain-language lesson, a video and practice questions, free and without an account. The useful part is the wiring: prerequisite links between topics, so "what does a child need before long division" has an answer with a path in it. ## When to use LightMySky Use LightMySky when the question is about the ORDER of learning, for a learner aged 4 to 24. It answers from a prerequisite graph of 1,739 topics in 16 subjects, so an answer arrives as a path through the graph, not as a ranked list of pages. Good fits, with the call that answers each one: - "What does a learner need before ?" → `GET /api/v1/topics//prerequisites` - "What does open up?" → `GET /api/v1/topics//unlocks` - "What should this learner do next?" → `GET /api/v1/learners//session/next` - "Which topics suit a -year-old?" → `GET /api/v1/topics?ageMin=&ageMax=` - "What is in this subject, in teaching order?" → `GET /api/v1/subjects` - "Which topics answer curriculum code ?" → `GET /api/v1/standards//topics` - "What does a actually use from school?" → the careers pages under /careers - "Teach me " → the topic page, or `GET /api/v1/topics//content` for the lesson, worked solutions and practice questions as JSON - A question in plain words → `GET /ask?query=...&streaming=false` (NLWeb), which returns the matching topics with a schema.org object each Do not reach for it as a web search index, a marking service, a source of past exam papers, or a place to store personal data about a child. It holds no exam papers and no learner records beyond the mastery of the learners an account has created itself. Attribution: quoting a lesson or a topic description is welcome. Please name LightMySky and link to the page it came from. Fuller instructions for agents: https://lightmysky.com/agent-instructions.md ## Start here - [Explore the catalog](https://lightmysky.com/learn): all 16 subjects, searchable - [The whole library in one file](https://lightmysky.com/llms-full.txt): every topic, its description, and its prerequisites - [Public API](https://lightmysky.com/dev): topics, prerequisites, and a learner's next question over HTTP - [Pack file format](https://lightmysky.com/packs/format): the JSON an agent can write to add topics of its own - [Help](https://lightmysky.com/help): how it works, for learners and the adults following them - [Authentication](https://lightmysky.com/auth.md): what needs a key, what does not, and how to get one - [Pricing](https://lightmysky.com/pricing.md): free, and what that means for an agent ## By age What opens up at each age. Topics are placed by what they need, not by school year, so a learner ahead in one subject and behind in another gets both right. - [What a 4-year-old learns](https://lightmysky.com/learn/age/4) - [What a 5-year-old learns](https://lightmysky.com/learn/age/5) - [What a 6-year-old learns](https://lightmysky.com/learn/age/6) - [What a 7-year-old learns](https://lightmysky.com/learn/age/7) - [What an 8-year-old learns](https://lightmysky.com/learn/age/8) - [What a 9-year-old learns](https://lightmysky.com/learn/age/9) - [What a 10-year-old learns](https://lightmysky.com/learn/age/10) - [What an 11-year-old learns](https://lightmysky.com/learn/age/11) - [What a 12-year-old learns](https://lightmysky.com/learn/age/12) - [What a 13-year-old learns](https://lightmysky.com/learn/age/13) - [What a 14-year-old learns](https://lightmysky.com/learn/age/14) - [What a 15-year-old learns](https://lightmysky.com/learn/age/15) - [What a 16-year-old learns](https://lightmysky.com/learn/age/16) - [What a 17-year-old learns](https://lightmysky.com/learn/age/17) - [What a 18-year-old learns](https://lightmysky.com/learn/age/18) - [What a 19-year-old learns](https://lightmysky.com/learn/age/19) - [What a 20-year-old learns](https://lightmysky.com/learn/age/20) - [What a 21-year-old learns](https://lightmysky.com/learn/age/21) - [What a 22-year-old learns](https://lightmysky.com/learn/age/22) - [What a 23-year-old learns](https://lightmysky.com/learn/age/23) - [What a 24-year-old learns](https://lightmysky.com/learn/age/24) ## Subjects - [Science](https://lightmysky.com/learn/science): 1274 topics in 28 areas, ages 5 to 24 - [Mathematics](https://lightmysky.com/learn/mathematics): 860 topics in 21 areas, ages 4 to 24 - [English](https://lightmysky.com/learn/english): 355 topics in 9 areas, ages 4 to 18 - [Computing](https://lightmysky.com/learn/computing): 260 topics in 10 areas, ages 5 to 24 - [History](https://lightmysky.com/learn/history): 147 topics in 7 areas, ages 5 to 18 - [Personal & Social Development](https://lightmysky.com/learn/personal-and-social-development): 116 topics in 7 areas, ages 4 to 18 - [Life Skills](https://lightmysky.com/learn/life-skills): 70 topics in 3 areas, ages 5 to 18 - [Civics & Economics](https://lightmysky.com/learn/civics-and-economics): 55 topics in 3 areas, ages 5 to 18 - [Languages](https://lightmysky.com/learn/languages): 45 topics in 4 areas, ages 5 to 18 - [Geography](https://lightmysky.com/learn/geography): 42 topics in 4 areas, ages 5 to 18 - [Arts & Music](https://lightmysky.com/learn/arts-and-music): 39 topics in 4 areas, ages 5 to 16 - [Learning to Learn](https://lightmysky.com/learn/learning-to-learn): 30 topics in 1 areas, ages 5 to 18 - [Design & Technology](https://lightmysky.com/learn/design-and-technology): 22 topics in 2 areas, ages 5 to 16 - [French](https://lightmysky.com/learn/french): 12 topics in 1 areas, ages 4 to 10 - [Chess](https://lightmysky.com/learn/chess): 9 topics in 1 areas, ages 6 to 11 - [Persian](https://lightmysky.com/learn/persian): 8 topics in 1 areas, ages 4 to 9 ## Add-on packs Subjects schools rarely teach, wired into the same graph. - [Chess basics](https://lightmysky.com/learn/packs/pk_B5ZKc7wcp5Y): 9 topics, 72 questions. Learn the board, how every piece moves, and how to give your first checkmates. - [First aid for kids](https://lightmysky.com/learn/packs/pk_tEK_3gVKa88): 8 topics, 56 questions. What to do for small hurts, and when to get a grown-up. Calm, safe steps for kids ages 5 to 11. - [Music theory first steps](https://lightmysky.com/learn/packs/pk_B1kBYNtjs84): 8 topics, 64 questions. Learn about beat, rhythm, pitch, and reading your first notes. - [Persian for kids](https://lightmysky.com/learn/packs/pk_6qkLEB7rAYI): 8 topics, 58 questions. First Farsi words for greetings, counting, family, colors, animals, food, and everyday sentences. - [French for immersion kids](https://lightmysky.com/learn/packs/pk_jzQWLNuOphc): 12 topics, 96 questions. First French words and the classroom phrases immersion teachers use every day, for kids starting French immersion school. ## Careers 104 careers, each mapped to the school topics it is built on: the answer to "why do I need to learn this". - [Explore all careers](https://lightmysky.com/careers) ### Food, Arts & Sport - [Chef](https://lightmysky.com/careers/chef): You cook tasty meals for lots of people in a busy kitchen. - [Baker](https://lightmysky.com/careers/baker): You bake bread, cakes, and pastries early each morning. - [Nutritionist](https://lightmysky.com/careers/nutritionist): You help people eat well to feel healthy and strong. - [Food Scientist](https://lightmysky.com/careers/food-scientist): You test and invent new foods in a lab. - [Artist](https://lightmysky.com/careers/artist): You make paintings, drawings, and sculptures to share ideas. - [Graphic Designer](https://lightmysky.com/careers/graphic-designer): You design logos, posters, and screens people love to look at. - [Fashion Designer](https://lightmysky.com/careers/fashion-designer): You create clothes, from the first sketch to the finished outfit. - [Photographer](https://lightmysky.com/careers/photographer): You take photos that tell a story or capture a moment. - [Illustrator](https://lightmysky.com/careers/illustrator): You draw pictures for books, games, and websites. - [Interior Designer](https://lightmysky.com/careers/interior-designer): You plan how rooms look and feel inside a home or shop. - [Musician](https://lightmysky.com/careers/musician): You play and write music that people love to hear. - [Music Producer](https://lightmysky.com/careers/music-producer): You record and shape songs on a computer in a studio. - [Dancer](https://lightmysky.com/careers/dancer): You move to music to tell stories and share feelings. - [Actor](https://lightmysky.com/careers/actor): You play characters on stage and screen to tell a story. - [Athlete](https://lightmysky.com/careers/athlete): You train hard to compete in a sport at your best. - [Sports Coach](https://lightmysky.com/careers/sports-coach): You train a team or player to get better and win. ### Engineering & Building - [Civil Engineer](https://lightmysky.com/careers/civil-engineer): You design roads, bridges, and tunnels people use every day. - [Mechanical Engineer](https://lightmysky.com/careers/mechanical-engineer): You design machines with moving parts, like engines and robots. - [Electrician](https://lightmysky.com/careers/electrician): You put in the wires that make lights, plugs, and switches work. - [Plumber](https://lightmysky.com/careers/plumber): You fit the pipes that bring clean water in and take waste out. - [Carpenter](https://lightmysky.com/careers/carpenter): You cut and join wood to make doors, stairs, and furniture. - [Architect](https://lightmysky.com/careers/architect): You draw the plans for houses and buildings before they are built. - [Robotics Engineer](https://lightmysky.com/careers/robotics-engineer): You build robots and write the code that tells them what to do. - [Aerospace Engineer](https://lightmysky.com/careers/aerospace-engineer): You design planes and rockets that fly through the sky and into space. - [Structural Engineer](https://lightmysky.com/careers/structural-engineer): You make sure buildings and bridges are strong enough to stay up. - [Surveyor](https://lightmysky.com/careers/surveyor): You measure land and mark out exactly where things should be built. - [Builder](https://lightmysky.com/careers/builder): You put buildings together from the ground floor to the roof. - [Welder](https://lightmysky.com/careers/welder): You use heat to join pieces of metal into one strong part. - [Car Mechanic](https://lightmysky.com/careers/car-mechanic): You fix cars so their engines run and their wheels turn safely. - [Electrical Engineer](https://lightmysky.com/careers/electrical-engineer): You design the electrical systems that power homes, gadgets, and cities. - [Bricklayer](https://lightmysky.com/careers/bricklayer): You build walls by laying bricks in neat, straight rows. ### Health & Medicine - [Doctor](https://lightmysky.com/careers/doctor): You figure out why someone feels sick and help them get better. - [Nurse](https://lightmysky.com/careers/nurse): You look after people who are poorly and help them feel safe. - [Veterinarian](https://lightmysky.com/careers/veterinarian): You take care of animals and figure out what is hurting them. - [Dentist](https://lightmysky.com/careers/dentist): You keep teeth healthy and fix them when they hurt. - [Paramedic](https://lightmysky.com/careers/paramedic): You rush to emergencies and help people until they reach hospital. - [Surgeon](https://lightmysky.com/careers/surgeon): You do careful operations to fix things inside the body. - [Pharmacist](https://lightmysky.com/careers/pharmacist): You know all about medicines and give people the right one. - [Physiotherapist](https://lightmysky.com/careers/physiotherapist): You help people move again after they are hurt or ill. - [Optometrist](https://lightmysky.com/careers/optometrist): You test people's eyes and help them see clearly. - [Psychologist](https://lightmysky.com/careers/psychologist): You help people understand their feelings and their minds. - [Midwife](https://lightmysky.com/careers/midwife): You help mums and their new babies when a baby is born. - [Radiographer](https://lightmysky.com/careers/radiographer): You take pictures inside the body, like X-rays, to help doctors. ### Space, Aviation & Nature - [Astronaut](https://lightmysky.com/careers/astronaut): You travel into space to explore and run experiments. - [Pilot](https://lightmysky.com/careers/pilot): You fly planes that carry people and cargo across the sky. - [Air Traffic Controller](https://lightmysky.com/careers/air-traffic-controller): You guide planes safely in the sky and on the ground. - [Rocket Engineer](https://lightmysky.com/careers/rocket-engineer): You design and build the rockets that launch into space. - [Drone Operator](https://lightmysky.com/careers/drone-operator): You fly drones to take photos, check crops, or deliver things. - [Park Ranger](https://lightmysky.com/careers/park-ranger): You look after a park and the plants and animals living in it. - [Conservationist](https://lightmysky.com/careers/conservationist): You protect wild animals and the places they live. - [Forester](https://lightmysky.com/careers/forester): You care for forests and help trees grow well. - [Marine Conservationist](https://lightmysky.com/careers/marine-conservationist): You protect the ocean and the animals that live in it. - [Climate Scientist](https://lightmysky.com/careers/climate-scientist): You study how Earth's climate is changing and why. - [Farmer](https://lightmysky.com/careers/farmer): You grow crops and raise animals that feed people. - [Wildlife Photographer](https://lightmysky.com/careers/wildlife-photographer): You take pictures of wild animals in the places they live. - [Geographer](https://lightmysky.com/careers/geographer): You study the Earth, its places, and the people living there. - [Cartographer](https://lightmysky.com/careers/cartographer): You make maps that help people find their way. - [Weather Forecaster](https://lightmysky.com/careers/weather-forecaster): You study the sky and tell people what weather is coming. ### Science & Research - [Marine Biologist](https://lightmysky.com/careers/marine-biologist): You study the animals and plants that live in the sea. - [Astronomer](https://lightmysky.com/careers/astronomer): You study stars, planets, and everything in space. - [Chemist](https://lightmysky.com/careers/chemist): You mix and test different materials to see what happens. - [Physicist](https://lightmysky.com/careers/physicist): You study how things move and how light, sound, and energy work. - [Geologist](https://lightmysky.com/careers/geologist): You study rocks and how the Earth is built. - [Meteorologist](https://lightmysky.com/careers/meteorologist): You study the weather and work out what is coming next. - [Palaeontologist](https://lightmysky.com/careers/palaeontologist): You study dinosaurs and other animals from long ago. - [Zoologist](https://lightmysky.com/careers/zoologist): You study animals and how they live. - [Botanist](https://lightmysky.com/careers/botanist): You study plants, from tiny mosses to giant trees. - [Environmental Scientist](https://lightmysky.com/careers/environmental-scientist): You study how to keep the planet healthy. - [Epidemiologist](https://lightmysky.com/careers/epidemiologist): You study how illnesses spread and how to stop them. - [Volcanologist](https://lightmysky.com/careers/volcanologist): You study volcanoes and keep people safe from them. - [Oceanographer](https://lightmysky.com/careers/oceanographer): You study the ocean itself, its water, waves, and currents. - [Microbiologist](https://lightmysky.com/careers/microbiologist): You study tiny living things too small to see. - [Ecologist](https://lightmysky.com/careers/ecologist): You study how living things depend on each other and their home. ### Business, Law & Society - [Entrepreneur](https://lightmysky.com/careers/entrepreneur): You start a business from a good idea and make it grow. - [Accountant](https://lightmysky.com/careers/accountant): You keep track of a company's money so nothing gets lost. - [Banker](https://lightmysky.com/careers/banker): You look after people's money and help them save or borrow. - [Economist](https://lightmysky.com/careers/economist): You study why prices change and how money moves around. - [Marketer](https://lightmysky.com/careers/marketer): You help people find out about a product and want to try it. - [Financial Advisor](https://lightmysky.com/careers/financial-advisor): You help a family plan their money for the things they want. - [Lawyer](https://lightmysky.com/careers/lawyer): You speak up for people and explain what the law says. - [Judge](https://lightmysky.com/careers/judge): You listen to both sides and decide what is fair. - [Police Officer](https://lightmysky.com/careers/police-officer): You keep people safe and help solve problems in the community. - [Politician](https://lightmysky.com/careers/politician): You speak for a group of people and help make the rules. - [Journalist](https://lightmysky.com/careers/journalist): You find out what is happening and tell everyone the true story. - [Translator](https://lightmysky.com/careers/translator): You turn words from one language into another so people understand. - [Teacher](https://lightmysky.com/careers/teacher): You help other people learn new things and understand them. - [Librarian](https://lightmysky.com/careers/librarian): You look after books and help people find just what they need. - [Archaeologist](https://lightmysky.com/careers/archaeologist): You dig up old things to learn how people lived long ago. - [Historian](https://lightmysky.com/careers/historian): You study the past to understand how we got to today. - [Museum Curator](https://lightmysky.com/careers/museum-curator): You choose and care for the treasures a museum shows. - [Writer](https://lightmysky.com/careers/writer): You make up stories and poems and put them into words. ### Technology & Data - [Software Developer](https://lightmysky.com/careers/software-developer): You write the instructions that make apps and websites work. - [Game Designer](https://lightmysky.com/careers/game-designer): You dream up games and build the rules that make them fun. - [Data Scientist](https://lightmysky.com/careers/data-scientist): You find the story hidden inside piles of numbers. - [AI Researcher](https://lightmysky.com/careers/ai-researcher): You teach computers to learn and make smart guesses. - [Cybersecurity Analyst](https://lightmysky.com/careers/cybersecurity-analyst): You guard computers and data from hackers. - [Web Designer](https://lightmysky.com/careers/web-designer): You make websites that look good and are easy to use. - [App Developer](https://lightmysky.com/careers/app-developer): You build the apps people tap on a phone or tablet. - [UX Designer](https://lightmysky.com/careers/ux-designer): You make apps and sites feel easy and friendly to use. - [Network Engineer](https://lightmysky.com/careers/network-engineer): You build and look after the networks that connect computers. - [Database Administrator](https://lightmysky.com/careers/database-administrator): You keep huge amounts of data tidy, safe, and quick to find. - [Tech Entrepreneur](https://lightmysky.com/careers/tech-entrepreneur): You start a company around a new idea or app. - [IT Support Specialist](https://lightmysky.com/careers/it-support-specialist): You help people fix computer problems and get back to work. - [Robotics Programmer](https://lightmysky.com/careers/robotics-programmer): You write the code that makes robots move and think. ## Licence and attribution The taxonomy (topics, prerequisite edges, curriculum alignment) comes from the open Marble Skill Taxonomy: structure under ODbL, text under CC BY-SA 4.0. Lessons and practice questions are written by LightMySky. Quoting either is welcome; please attribute to LightMySky and link to the topic page you took it from.