For teachers

Scratch for Java is made for the moment a class has outgrown Scratch but is not ready to start Java from an empty file. Stage, sprite, costume, move, say, when key pressed: the names stay the same, so your students can bring what they already know with them and spend their attention on what is actually new, which is classes, objects, methods and variables.

This page helps you plan a unit with it.

Where your students work

	Good for	What you prepare
Browser	The first lessons, homework, computers you cannot install anything on	Nothing. The editor is built into every tutorial.
Studio	A whole unit on school computers, working offline	Install Studio. Java and the library are included.
BlueJ / VS Code	Courses that already use one of them	Add the library as described in Setup.

Starting in the browser and moving to Studio or BlueJ later works well. The code stays the same. Only the void main() at the top becomes a class of its own.

The seven tutorials as a unit

Each tutorial adds one idea to the previous ones and ends with the whole project running in the page. Plan roughly one lesson each. The hedgehog game and the last chapter take longer.

	Tutorial	Builds on (Scratch)	New in Java	Typical stumbling blocks
1	Your first program	Sprites, costumes, forever	A class for the stage, new, run()	Forgetting this.add(...); typos in costume names
2	Make it Walk	next costume, wait	Timers instead of wait, AnimatedSprite, a boolean	Wanting a wait inside run()
3	Catch the Coins	Variables, pick random, touching?	Fields, a for loop, one class for many coins	Where the score lives, and how a coin reaches it
4	Red Light, Green Light	broadcast, when I receive	Constructor parameters, String.equals	Comparing strings with ==
5	Guess the Number	ask and wait, answer	if/else if, turning text into a number	ask does not wait: the answer arrives in a later frame
6	Bouncing Hedgehog	A whole small game	Combining everything, using your own pictures	Image files in the wrong folder
7	Dodge the Rocks	Several backdrops as screens	Several stages and a Window	Trying to reset a game by hand

Every tutorial page names the Scratch block it replaces, so your students can keep the vocabulary they already have. The Scratch → Java cheat sheet puts all of them on one page, and it is worth handing out. Differences to Scratch explains the few places where Java needs a different way of thinking. The most important one is that there is no forever and no wait inside a sprite.

The tutorials end with Things to try: small extensions with a hint and a solution to unfold. They work well for students who finish early.

Choosing an approach

You can introduce objects from the first lesson, or start with one class and bring in classes later. Both work with this library. Multiple Approach Design shows the same project in each style, so you can choose the one that fits your course.

If your course works with the classes of the NRW Zentralabitur (List, Queue, Graph, …), use the NRW version of the library: Abiturklassen NRW.

Material in German

The German material lives in Hyperbook Informatik:

• Grundlagen der Programmierung mit Java, a learning path from the first program to classes and objects.
• Spielwerkstatt, in which each student builds a 2D adventure game over the Einführungsphase and on into the Qualifikationsphase, with a developer diary for reflection.

The Spielwerkstatt is a natural next step after the seven tutorials. Each chapter of the learning path ends with game mechanics that apply what was just learned, and students choose one for their own game.

Assessing the work

A finished tutorial shows that a student followed the steps. It does not show that they understood them. Assess the student's own change and their explanation of it instead:

	Developing	Secure	Extending
Java model	Can point at the stage and a sprite	Explains fields, methods and what one call of run() does	Explains why two objects of the same class behave independently
Sequencing	Uses a working example	Uses timers and variables instead of waiting	Explains in which order events happen
Testing	Runs it once and watches	Tests edges, collisions and scoring on purpose	Writes down what was tested and what happened
Reflection	Describes the change	Gives reasons for it	Compares two ways of doing it and justifies the choice

Working offline: the course pack

Download the course pack. It holds every tutorial as an ordinary Java project, once as a starter (the previous lesson's result) and once as a checkpoint (the finished state), with the lesson text, these teacher notes and the assessment grid.

In Studio, Project → Import course pack copies the library into every project, so nothing needs to be downloaded in class. Give each student their own copy of the folder. Checkpoints are there to get someone unstuck, not to be handed in.

Before the first lesson, try it once on a school computer without internet: import the pack, run the first project, save it, close Studio and open it again.

When something goes wrong

It doesn't work! collects the mistakes beginners make most often, and what the error messages mean. It is written for students, so you can send them there first.