You Already Know This

1 Sort these eight everyday things 3 MIN

None of these are about computers. Read each one and pick the description that fits it best. There is no trick and nothing here is graded — go with your gut.

0 of 8 sorted

2 What you just did 1 MIN

Those four groups have names. You sorted them before anyone taught you what they were called.

Every program ever written — every app on your phone, every game you have played — is built out of these four ideas and nothing more exotic. You will spend this year learning to write them down precisely enough that a machine can follow them.

Step by step

Sequence

Instructions that run in order, one after another. Change the order and you change the result.

Depends on something

Selection

The program checks whether something is true, then picks a path. Often called an if statement.

Happens over and over

Repetition

The same instructions run again and again until a condition is met, or a set number of times. A loop.

Waits for a signal

Event

Nothing happens until something happens — a tap, a shake, a message arriving. Then the code runs.

Number 4 on your list, in the blocks you will build with next class

“When someone texts you, your phone buzzes.”

→

whenButton1.Click

callCamera1.TakePicture

Same shape: wait for a signal, then do something. The gold block is the waiting. The purple block is the doing. Those are the actual blocks from the first app you are going to build — it takes a picture when the button is tapped.

3 Two questions, then you are done 2 MIN

Name one app you use almost every day. What is one thing about it that annoys you, or that you would change?

Be specific. “It's slow” is less useful than “it takes four taps to do the one thing I always want.”

Somebody decided it would work that way. Why might it matter to be a person who makes the technology, and not only a person who uses it?

There is no right answer here. I actually want to know what you think.

Where this goes

Hold on to that second question. It is one of the two questions this whole first unit is built around, and you will answer it again at the end of it. It is worth seeing how your answer changes.

Finished early? Try the hard part +3 MIN

Here is the catch. A person can follow a vague instruction. A machine cannot — it does exactly what you say, not what you meant. For each pair, pick the one a machine could actually follow.

Keep going

Sort all eight above and the rest of the page opens up.