Every course starts with a guided requirements and setup module. You will always find a complete free path—including browser simulators when hardware, cloud compute, GPUs, or paid AI APIs would otherwise be needed.
Course catalog
Showing 25 of 25 courses
Course 1
Learn to decompose problems, design precise algorithms, trace decisions, and debug logic without needing prior coding experience.
The always-free pathway combines guided browser concept simulations with learner-created planning files. The simulator does not execute code or replace project software.
Explore courseCourse 2
Create animated stories and increasingly challenging games with Scratch events, variables, clones, collisions, and reusable blocks.
The verified Scratch browser editor supports learner-created project files, while the C4T page adds guided concept practice. No paid option is required.
Explore courseCourse 3
Write and debug Python programs with variables, input, decisions, loops, functions, validation, and clear output.
The always-free pathway combines guided browser concept simulations with learner-created Python files made in a freely installable or open tool. The C4T page does not execute Python.
Explore courseCourse 4
Build larger Python command-line projects using collections, files, JSON, reusable functions, validation, dependencies, and systematic debugging.
The always-free pathway combines guided concept simulations with learner-created Python, JSON, and test files made in freely installable or open tools. The C4T page does not execute them.
Explore courseCourse 5
Design maintainable Python software with classes, composition, interfaces, type hints, custom errors, modules, tests, and deliberate refactoring.
The always-free pathway combines guided design simulations with learner-created Python and test files made in freely installable or open tools. The C4T page does not run an IDE or tests.
Explore courseCourse 6
Build semantic, accessible, responsive multi-page websites with HTML, CSS, Flexbox, Grid, forms, and strong visual hierarchy.
The always-free pathway combines responsive-layout concept simulations with learner-created HTML and CSS files made in a freely installable or open editor. A domain and paid host are optional.
Explore courseCourse 7
Turn static pages into reliable browser applications with JavaScript, DOM updates, events, validation, storage, APIs, async work, and explicit state.
The always-free pathway combines guided browser-behavior simulations with learner-created JavaScript files made in freely installable or open tools. The C4T page does not execute code, store app data, or call APIs.
Explore courseCourse 8
Practice version history, branches, pull requests, review, conflicts, documentation, licenses, releases, and CI through guided concepts and learner-created local project files.
The always-free pathway combines branch-and-merge concept simulations with learner-created patch, review, and documentation files. A hosted repository account is optional and is not listed as a paid option.
Explore courseCourse 9
Invent with virtual or physical micro:bits using inputs, LEDs, motion, sound, radio, sensor data, MakeCode, and MicroPython.
Complete every activity with the included browser simulator—physical hardware is optional.
Explore courseCourse 10
Design and debug safe simulated or physical circuits, sensors, motors, state machines, feedback systems, and mobile robots.
Complete every activity with the included browser simulator—physical hardware is optional.
Explore courseCourse 11
Build a validated database-backed web API using HTTP, REST, JSON, Python routes, relational SQL, authentication basics, and useful errors.
The always-free pathway combines HTTP and data concept simulations with learner-created API, SQL, and test files made in freely installable or open tools. The C4T page does not run servers, SQL, or tests.
Explore courseCourse 12
Design the systems for a complete game using guided concept simulations and learner-created planning and code files, with optional locally installed Unity workflows.
The always-free pathway combines game-system concept simulations with learner-created design and C# files made in freely installable or open tools. Running Unity and publishing a native build are optional.
Explore courseCourse 13
Clean, explore, summarize, visualize, and communicate CSV or JSON data with NumPy, pandas, Matplotlib, reproducible notebooks, and careful claims.
The always-free pathway combines data concept simulations with learner-created analysis files made in freely installable or open tools and learner-selected non-sensitive data. The C4T page does not run notebooks.
Explore courseCourse 14
Understand what AI and machine learning can and cannot do through classification, regression, clustering, generation, data splits, uncertainty, bias, privacy, and use-case decisions.
The always-free pathway uses guided AI concept simulations and learner-created analysis files. It does not call a model API or require an account, API key, GPU, or paid chatbot.
Explore courseCourse 15
Plan consent-respecting image, sound, or pose data; explore class balance, confidence, and errors with guided concepts; and document an optional learner-managed model workflow.
The always-free pathway combines model-training concept simulations with learner-created dataset plans and project files. The C4T page does not collect media or train a model; cameras, microphones, cloud training, and paid tools are optional.
Explore courseCourse 16
Build reproducible scikit-learn pipelines, compare KNN, linear and logistic regression, and decision trees, and evaluate predictions with suitable metrics.
The always-free pathway combines ML concept simulations with learner-created Python and analysis files made in freely installable or open tools. The C4T page does not run notebooks or train models.
Explore courseCourse 17
Design a secure IoT system with simulated or physical GPIO, sensors, Python control, time-series data, MQTT, dashboards, remote actions, authentication, and credential safety.
Complete every activity with the included browser simulator—physical hardware is optional.
Explore courseCourse 18
Evaluate and design TinyML systems with sensor windows, classification, quantization, constrained memory, latency, deployment, accuracy, power, and local-inference privacy.
Complete every activity with the included browser simulator—physical hardware is optional.
Explore courseCourse 19
Build rigorous ML comparisons with feature engineering, pipelines, cross-validation, tuning, imbalance handling, ensembles, leakage checks, calibration, interpretation, and sliced error analysis.
The always-free pathway combines evaluation concept simulations with learner-created pipeline and report files made in freely installable or open tools. The C4T page does not run searches, notebooks, or models.
Explore courseCourse 20
Understand and evaluate neural networks, optimization, CNNs, augmentation, transfer learning, detection, segmentation, tracking, GPU trade-offs, and responsible computer vision.
The always-free pathway combines neural-network concept simulations with learner-created experiment and model-card files. The C4T page does not provide checkpoints or train models; GPU hardware and paid compute are optional.
Explore courseCourse 21
Explore tokenization, embeddings, classification, entities, transformers, attention, prompts, structured output, retrieval, hallucination checks, adaptation, evaluation, and responsible deployment.
The always-free pathway combines NLP and retrieval concept simulations with learner-created prompt, document, and evaluation files. The C4T page does not supply documents, embeddings, or model output and does not call a paid API.
Explore courseCourse 22
Turn research questions into reproducible ML experiments with literature context, dataset provenance, baselines, controls, uncertainty, ablations, sensitivity checks, leakage prevention, and scientific reporting.
The always-free pathway combines scientific-method simulations with learner-created protocols, notebooks, and reports made in freely installable or open tools using learner-selected accessible sources. The C4T page does not provide datasets or run experiments.
Explore courseCourse 23
Package, version, deploy, monitor, and recover ML services using local containers and simulations for batch, real-time, registries, pipelines, CI/CD, drift, canaries, costs, and incidents.
The always-free pathway combines MLOps concept simulations with learner-created service, container, monitoring, and incident files made in freely installable or open tools. The C4T page does not run or deploy services; paid cloud resources are optional.
Explore courseCourse 24
Design and supervise coding-agent workflows with repository exploration, plans, diffs, tests, tool schemas, MCP, APIs, permissions, approvals, and defenses against prompt injection and untrusted output.
The always-free pathway combines agent-workflow concept simulations with learner-created task, tool-schema, permission, diff-review, and evaluation files. The C4T page does not provide a repository, model, tools, or test runner; paid model access is optional.
Explore courseCourse 25
Engineer secure agent runtimes, sandboxes, traces, evaluations, graders, routing, multi-agent roles, loop controls, approvals, rollbacks, adversarial tests, and measurable improvement cycles.
The always-free pathway combines multi-agent concept simulations with learner-created harness, trace, grader-design, routing, and security files. The C4T page does not provide a runtime, repository, model, grader, or sandbox; paid model and evaluation services are optional.
Explore courseNot sure where to start?
Each path is an ordered route through the catalog, from the first course to a capstone project. Recommended prior courses are advisory — you can always jump straight in.