Week 01 · Wednesday: A computer is a system (Inside the Machine G3 to G5)

Wednesday: Input, process, output

A neighbor brings a music player to the Fix-It Bay. "Press play and nothing happens!" Rocket says. He pushes the button five times, fast.

Raven holds up a hand. "What do you notice?" she asks. "Does the button click? Does the screen change? Does any sound come out?"

Nova draws three glowing boxes in the air. "Every computer does three things in order," she says. "Would you like a hint? Find out which step is missing."

Three steps, always in order

Every computer follows the same path. Information goes in, the computer works on it, and a result comes out.

Input is the information going in. A button press, a tap or a spoken word is input.

Process means the processor follows instructions to work on the input.

Output is the result coming out. A sound, a picture or a flashing light is output.

Input: press play

Process: find the song and read it

Output: music plays

Say the three words in order: input, process, output. The order never changes.

What you do	Input	Process	Output
Type a word	Key presses	Work out which letters	Letters appear on the screen
Take a photo	Light hits the camera	Turn light into a picture	Photo shows on the screen
Ask for the weather	Your voice	Understand the words, find the answer	A voice reads the weather

Find the missing step

In the Fix-It Bay, the crew tests each step. The play button clicks, so the input works. The screen shows a song name, so the processor got the message.

No sound comes out. The output step is the problem. Raven turns the volume up. The music plays!

Testing one step at a time is how real technicians work. You will use this all year.

PUT THE STEPS OF A PHOTO IN ORDER

Tap a card.
Then tap its spot.

1First

2Next

3Last

INPUT OR OUTPUT?

Read the question.
Tap your answer.

You press a key on a keyboard. Which step is that?

A speaker plays a song. Which step is that?

The processor works out which letter you typed. Which step is that?

In the story, which step was the problem: input, process or output?

WHY THIS EXERCISEThe input and process steps worked. Only the sound was missing, and sound is output.

PUT THE PATH OF A SPOKEN QUESTION IN ORDER

?The speaker reads the answer to you
?The processor works out the answer
?The microphone takes in your voice
?You say a question out loud

WHY THIS EXERCISEEvery computer task follows input, process, output. Spotting the order helps you find where it breaks.

Statement	True or false?
Output always happens before input.	?
A tap on a touchscreen is input.	?
The processor does the process step.	?
A picture on the screen is input.	?

WHY THIS EXERCISEKeeping these three words straight lets you describe any computer task.

The crew writes it down

Raven keeps a case log in the Fix-It Bay. For each case she writes three lines: input, process, output.

Next to each line she writes works or broken. The broken line shows where to look.

For the music player, her log said: input works, process works, output broken.

A log like this turns a big mystery into one small question.

In Raven's log, how many lines does she write for each case?

WHY THIS EXERCISEInput, process and output are three steps, so the log has three lines.

Try it

Pick one thing you do with a device, like sending a message.
Say the input, the process and the output out loud.
Draw three boxes and write one step in each.

Rocket pressed the button five times fast. Raven tested one step at a time. Which way is better for finding a problem? Explain why.

You followed information all the way through a machine! Tomorrow you will find out where a computer keeps things for later.