First, Then, Next: Your First Coding Sequence
When you make a peanut butter sandwich, you get the bread first, then spread the peanut butter, then put the slices together. If you did it in the wrong order — like spreading peanut butter before you even have bread out — it would be a mess! Computers need the same kind of first-then-next list. We call that list a sequence.
What You'll Learn
What a sequence is Why the order of steps matters How to give directions using first, then, next, and last How to find and fix a step that is out of order
What Is a Sequence?
A sequence is a list of steps that a computer, a robot, or even you follow in order, one at a time, from top to bottom. Skip a step or do it out of order, and things go wrong — just like the sandwich!
Try It: Robot Directions
Imagine giving a toy robot directions to grab a cup: Step 1, walk forward 3 steps. Step 2, turn right. Step 3, walk forward 2 steps. Step 4, pick up the cup. Now imagine swapping Step 2 and Step 4 — the robot would try to pick up a cup that isn't even there yet!
When steps are in the wrong order and cause a mistake, we call that a bug. Finding the wrong step and fixing the order is called debugging — just like a real coder does!
Sequences Are Everywhere
Getting ready for school is a sequence too. You put on underwear before pants, not after! Brushing your teeth, tying your shoes, and making breakfast all follow a first-then-next order.
Put these getting-ready-for-school steps in order by matching each step to its position.
Terms
Definitions
Drag terms onto their definitions, or click a term then click a definition to match.
What do we call it when the steps in a sequence are in the wrong order and cause a mistake?
Which step comes first when brushing your teeth?
Be the Sequence
With a grown-up or friend, pick a simple task, like making a sandwich or packing a backpack. Draw 4 boxes in a row. In each box, draw or write ONE step in order: first, then, next, last. Give your drawn steps to someone else and see if they can follow them in the right order!
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