World 5 · Messages · Guide 4 of 5Free guide
Message chains
One message starts a program that sends the next message. That is a chain.
Meet a chain
A program under a 📬 hat can end with a send block of its own. Then hearing one message makes it send the next. Hook three programs together like that and you have a chain: the first one starts the second, and the second starts the third. Nobody needs to know about anyone except the next one.
Listen for one colour, send the next one. That is a link in the chain.
See it work
Three bugs, three programs, one ▶. Read them in order, then watch the message travel.
🐝
🦋
The ladybird sent red. The bee heard red, moved, and sent blue. The butterfly heard blue and flew. One ▶, and the message went all the way down the chain.
Your turn
Now you're the programmer.
Can you run the middle of the relay?
Make the 🦊 wait for 🔴, run to its mark, then send 🔵 to the 🐢.
The rabbit's program
The turtle's program
Blocks
Your program
Go further
What if the chain is broken?
Take the send block off the end of your program. The fox still hears the rabbit and still runs — but it never passes the baton on, so the turtle waits at its mark for ever. Break one link, and everything after it never starts.
For grown-ups
Steps that each trigger the next are called a pipeline or a chain of callbacks — how a factory line, a video upload or a checkout process moves work along.
Keep going
Next in World 5Make: The Drum Machine →Where this goes
Make a game other kids can play
The blocks on this page are a first taste. In a Kubrio project your kid builds a real game — powers, triggers, levels and all — and other kids get to play it.