What is an algorithm?

A set of steps for doing something, in an order that works. Making a jam sandwich is one, and so is brushing your teeth: a computer needs its steps written out in the same way, which is why this is where primary computing starts.

Is there only one right order?

No, and that is deliberate. In every job here two of the steps do not depend on each other, so they can go either way round: it does not matter whether you get the bread out before or after you open the jam. What matters is that both happen before you spread anything.

Why does it not tell you when you are wrong?

Because what happened is a better answer than a cross. The board says the jam went on the plate, and a class can see for themselves which step needed to come first. Nothing in these tools is scored.

Can we use our own job?

Not yet. The board has to know which steps depend on which, and that is what makes the wrong order funny rather than just wrong, so each job is written out here. Making up a fourth one with a class and acting it out is the natural next thing to do anyway.

Order the Algorithm

Computing · Reception–Year 2

Put the steps in order, press Run, and see what happens.

About the order the algorithm

Four instruction cards for an everyday job, and four numbered places to put them. Tap a card and it goes in the next place, or drag it where you want it. Press Run and the board does exactly what it was told, in the order it was told.

The point is what happens when the order is wrong. Spread the jam before the bread is out and the board says so: there is no bread yet, so nothing happens to it. That is the whole idea of an algorithm in one press, and it is funnier than being told you are wrong.

Nothing is marked. There is no score, no cross and no “try again”: the board says what happened and the class works out why, which is the same rule the shop till follows when you count out too much change.

Three jobs to choose from: making a jam sandwich, brushing your teeth and planting a seed. Each has two steps that can go either way round, so the answer is not one line a class can guess. What matters is which steps depend on which.

The picture is worked out from the steps that actually worked, so it can never show a sandwich the order did not make.

How to use it on your whiteboard

1Tap a card at the bottom to put it in the next place, or drag it to the place you want.
2Drag a card onto another one to swap the two over.
3Ask the class to read the steps out in order before you press Run.
4Press Run, and the board does what it was told.
5Try it deliberately in the wrong order: that is the best press on the board.

Questions

What is an algorithm?: A set of steps for doing something, in an order that works. Making a jam sandwich is one, and so is brushing your teeth: a computer needs its steps written out in the same way, which is why this is where primary computing starts.
Is there only one right order?: No, and that is deliberate. In every job here two of the steps do not depend on each other, so they can go either way round: it does not matter whether you get the bread out before or after you open the jam. What matters is that both happen before you spread anything.
Why does it not tell you when you are wrong?: Because what happened is a better answer than a cross. The board says the jam went on the plate, and a class can see for themselves which step needed to come first. Nothing in these tools is scored.
Can we use our own job?: Not yet. The board has to know which steps depend on which, and that is what makes the wrong order funny rather than just wrong, so each job is written out here. Making up a fourth one with a class and acting it out is the natural next thing to do anyway.