Twelve interactive levels of the thinking an intro computer science course assumes you already have. No C++, no compiler, nothing to install — just the reps everyone else in the room already did.
CSCI-135 lists CSCI-100 as its prerequisite. That earlier course has no programming language in it at all — it is a whole semester of algorithms and problem solving, which is exactly what CSCI-135 says it emphasises most.
So the students sitting around you have spent months breaking problems apart before anyone showed them a compiler. When the lecturer says “decompose this”, they have done it fifty times. That is the gap — and it is not a gap in intelligence or in C++. It is a gap in reps.
This track is those reps. Twelve levels, no programming language, nothing to install. Do them before the semester starts and you walk in level with the room.
CSCI-135: “Emphasis will be placed on problem analysis and on the subsequent development of algorithms… A major focus of the lectures will be to provide an overview of real-world problem solving concepts and top-down software design.” Read that twice. The emphasis is not on C++ — C++ is just what you write the answer in.
Each level is one idea, one drawn diagram, one thing you drive with your hands, and one exercise for two people. Around two and a half hours for all twelve — and it is meant to be done over several days, not in one sitting.
{progress.track_markup()}Drive a robot into a wall on purpose and find out what an algorithm really is.
12 min · the literal machine 02Top-down design, made physical. Cut a task apart until every piece is obvious — then name the pieces.
14 min · the breakdown 03The only three shapes any program is made of. Press play and watch the path light up.
13 min · the three shapes 04The single highest-value skill in the course. Step through a loop and watch every value change.
15 min · the trace table 05Watch three unrelated problems collapse into one shape once you strip the nouns out.
12 min · the same shape 06Race two correct methods and meet the question that turns programming into computer science.
13 min · the race 07Step a real processor one instruction at a time, then watch one missing semicolon stop everything.
14 min · the machine 08Flip eight switches to build any number, turn letters into numbers, and see why 0.1 + 0.2 is not 0.3.
14 min · bits and bytes 09Variables, and the equals sign that does not mean equals. Watch a box quietly turn 3.9 into 3.
14 min · the box 10Truth tables you can flip, then one wrong joining word putting a three-year-old on a rollercoaster.
13 min · the logic bench 11The three kinds of wrong, and a real bug that only one number in the world can reveal.
14 min · the test bench 12Watch a sort work honestly and slowly, then meet the idea that makes the real ones fast.
13 min · the sortEvery level ends with an exercise for two people with real roles. That is not decoration — the course you missed was built on group exercises, and some of these ideas only land when someone else follows your instructions literally and gets it wrong.
Every section has a button that writes a question for you — one that already explains you are a beginner, which course you are taking, and what you are working on. Copy it, paste it into ChatGPT or Claude, and you get an answer pitched at you rather than at a computer science graduate.
There is no C++ here, and nothing to install. That is on purpose. Setting up a Mac to compile C++ — and making sure your laptop agrees with the machines in the closed lab — is a genuinely fiddly afternoon, and doing it before you can think in algorithms is how people end up believing they are bad at programming when they are actually just fighting a compiler.
You do not need to have written a line of code, seen a terminal, or know what a compiler is. Nothing here asks you to install anything or type any code. If you can read this page, you can do all six levels.
It is also genuinely useful if you have programmed a bit and it never quite clicked — because the thing that usually did not click is in here, not in the syntax.
← back to all modules · stuck on anything? ask peter.