CBuilderClassical machine learning· about 45 min· fundamentals that rarely change· verified 2026-09-20· EN
Project: train an image classifier in the browser
Be able to collect examples, train and test a classifier, and report when it works and when it does not.
Prerequisites
Intuition
The project: build an image classifier in the browser (Teachable Machine) with three classes of your own choosing — scissors/pencil/eraser, say, or three hand signs.
Requirements:
- At least 30 pictures per class, with variation.
- Set aside 10 pictures per class that the model may not train on (the test set).
- Measure the accuracy on the test set: correct / 30.
- Find at least three pictures the model classifies wrongly and explain why.
A model without a test set is a guess about how good it is.
Interactive
A reporting template:
| Classes | scissors, pencil, eraser |
| Training pictures | 35 / 32 / 40 |
| Test pictures | 10 / 10 / 10 |
| Accuracy | 26/30 = 87 % |
| Mistakes | pencil→eraser ×2 (a short pencil), scissors→pencil (closed scissors) … |
| Improvement | more pictures of closed scissors; test again |
Also write: what would happen if someone else used the model with their objects and their lighting?
Mastery means
- Collects, trains and tests a classifier
- Reports the accuracy and concrete cases where it fails
Sign in to do the exercises and build your mastery up.
Sources
- Teachable Machine (Google, gratis) — free web service