The Critter Factory

Object-Oriented Programming is all about blueprints. You design one class (a blueprint), then stamp out as many objects as you like from it. Here, the blueprint is a Critter — and every critter you create is its own little creature with its own properties and methods.

One blueprint, many critters

A class describes what every critter has and can do. Each new Critter() is a separate object.

📐 class Critter

• color, name
• energy
• feed() · play() · speak()

➜

📐Classthe blueprint

🐣Objectone real critter

🎨Propertyits color, name, energy

⚡Methodan action it can do

Play it

Critter playground

Press New Critter to stamp objects from the blueprint. Click a critter to select it, then call a method on it. Watch the code you're writing appear below!

No critters yet — press “➕ New Critter”!

📝 The code your clicks are writing:

// your critter code shows up here…

What the blueprint looks like in code

This is the class behind every critter on this page.

class Critter {
  // the blueprint's starting values
  constructor(color, name) {
    this.color = color;
    this.name = name;
    this.energy = 40;
  }

  // methods = things a critter can do
  feed() { this.energy = this.energy + 25; }
  speak() { say("Hi, I'm " + this.name); }
}

let sparky = new Critter("blue", "Sparky");
sparky.feed();   // Sparky's energy is now 65

Now you code it

Code Lab: build with classes

Use the Critter blueprint to create objects and call their methods. Click blocks to build your program, then Run it to bring your critters to life.

📋 How this Code Lab works

Read the 🎯 Mission goal at the top.
Click a block on the left to add it to Your program. Lines run top to bottom.
Drag a block (or use ↑ ↓) to reorder; tap × to remove.
Press ▶ Run code — your critters appear and act out your code.
Green ✅ = solved (Next mission appears). Blue 💡 = a hint to try again.

💡 Tip: new Critter("blue") makes an object. sparky.feed() calls a method on that one object.

🧱 Code blocks

Click to add to your program.

📝 Your program

Runs top to bottom.

🐣 Your critters: