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Tutorial · Grade 330. Fragile Parcels

Send each fragile parcel to the Fragile Block. Send every other parcel to the Standard Block.

Scenario

Parcels arrive one at a time. Some parcels are fragile, and some are not.

Problem statement

Welcome to the mail room.

Parcels arrive one at a time. Some of them break easily, like a glass vase or light bulbs. These parcels have a FRAGILE label.

Fragile parcels go to the Fragile Block. All other parcels go to the Standard Block.

For each parcel, you make one choice: which block does it go to?

Right now there are no rules. The parcels wait and nothing moves.

Your task: build a rule that sends every fragile parcel to the Fragile Block. Then build a rule that sends every other parcel to the Standard Block.

Rules are checked from the top, and the first rule that is true wins. So the order of your rules matters.

What this teaches

How to make a yes-or-no choice: do one thing when something is true, and another thing when it is not.

Scroll down to build and test your solution.

Active controller

Apply & Run executes only the selected controller.

How a rule works

A rule has two parts:

WHEN <something is true> → DO <this action>

  • WHEN is a question about what is happening right now. For example: "Is it raining?" or "Is there a wall ahead?"
  • DO is what happens when the answer is yes.
  • The simulation runs one step at a time.
  • On each step, the rules are checked from top to bottom.
  • The first rule that is true wins. The rules below it are skipped for that step.
  • To change which rule wins, move it up or down the list.
  • If no rule is true, nothing happens on that step.
  • Some actions have more than one step, like "turn right, then move". You build these in the Functions tab.
  • Once a multi-step action starts, it finishes all its steps before the rules are checked again. It only stops early if the next step is not safe.
See an example

Two rules for deciding about an umbrella:

1  WHEN isRaining  → take an umbrella
2  WHEN always     → leave the umbrella at home
  • It is raining. Rule 1 is true, so you take an umbrella. Rule 2 is skipped.
  • It is sunny. Rule 1 is false, so rule 2 is checked next. Rule 2 is always true, so you leave the umbrella at home.
  • Order matters. If rule 2 were on top, it would be true every day, and you would never take an umbrella.

Rule folders

Categorise cards without changing their global execution order.

No rules yet. Nothing will happen until you add at least one rule.