A metro network for learning to code
Every language is a line. Every module, a station.
C, C++, Python and Java, taught in depth and in plain English.
01 · The network
Four lines. Every part open.
Each language is its own line, and each module is a station on it. All four lines are open end to end, from the first program to the newest parts of each language. Where two lines teach the same idea, an interchange lets you change between them.
02 · How a station works
Five platforms at every station.
Every module, on every line, takes you through the same five platforms in the same order. The cards below are real samples from one station of the line you pick. Move the train with Next, the arrow keys, or a swipe.
03 · Inside a lesson
Every lesson is one train. Same coaches, same order.
Regular commuters know which coach stops by the exit, because the train is coupled the same way every day. Lessons work the same way. Five coaches run on every lesson; New words is coupled on when a lesson brings new terms, and Go deeper when there is optional extra detail.
04 · Try it now
Write a few lines of code. Right here.
C and C++ run in your browser: edit, press Run, break it on purpose and read the error. Python and Java show real programs with the output they printed when we checked them; the guides teach you to run them yourself.
Press Run to see what your program prints.
05 · Plan a route
Where are you boarding?
Three quick questions plan your route: your line, your level and your pace. Board straight away, and the guide opens at your level. Save the route on a metro card and it is kept for when accounts open.
06 · You decide
What should open next?
Every part of all four lines is open. Next on the map: a data structures and algorithms line in one of three languages, or a new JavaScript line. One vote per rider; the totals are live and come only from votes on this page. Get a metro card and we will tell you the day your pick opens.
07 · Checked, not guessed
Every output on the network is real.
Each guide shows what a program prints only after running it. These numbers come straight from the four guides.
08 · Free to ride
Your metro card.
One free card holds your route, your level and your scores, so everything is waiting when accounts open. Type your name to preview it; get the card to activate it and save it as an image.
Four lines, end to end. Your card is waiting.
Board any line today with no setup. Get a free metro card and your route, level and scores are saved for when accounts open, with a say in what opens next.