Welcome to Module 2 — core machine learning
Before we begin
You finished Module 1: vectors, dot products, noise, gradient descent, and a hands-on regression project. You already know how a model updates its weights. Module 2 asks the next questions:
What kinds of ML problems exist? How do we know if a model is actually good? And how do we build something people can use?
Module 2 is still beginner-friendly — plain language, worked examples, one real project. No PyTorch yet. You will use Python to train a classifier and Node.js + MongoDB to serve it like a small production app.
Figure
Module 2 at a glance
What Module 2 covers
| Topic | What you will understand |
|---|---|
| Supervised vs unsupervised | When you have labels vs when the model finds structure alone |
| Regression vs classification | Numeric predictions vs category choices |
| Overfitting / underfitting | When a model memorizes instead of generalizes |
| Train / validation / test splits | How to evaluate honestly without cheating |
| Metrics | Accuracy, precision, recall — and when accuracy lies |
Before you start
Required: complete Module 1 (or at minimum Lessons 1–4 + gradient descent intuition).
Nice to have: basic JavaScript/Node.js (for the project API). We provide copy-paste-ready snippets.
Install before the project:
- Python 3.10+ with
pip install scikit-learn numpy matplotlib - Node.js 18+ and MongoDB (local or Atlas free tier)
Lessons 1–6 are reading only. Lesson 8 (project) is where code matters.
How this connects to Module 1
| Module 1 idea | Module 2 use |
|---|---|
| Vectors & lists of numbers | Email features become word-count vectors |
| Loss & gradient descent | Classifiers still minimize error — different loss functions |
| Overfitting (intro in welcome) | Now the central topic with fixes |
| Linear regression project | Same training loop spirit — new problem type (spam/ham) |
Full course context
- Math & intuition — done
- Core machine learning ← you are here
- Neural networks
- PyTorch fundamentals
- Deep learning architectures
- Transformers & GenAI
- Agents & tool use
- Production & deployment
Ready?
Open the first technical lesson when this page makes sense: