Week 01 · Thursday: Design Before Code (Intro to CS 9-10)

Thursday: One Piece at a Time

Comet spreads the storyboard cards across the workbench. "Now we build all three screens at once, tonight!"

Wren picks up the Plant Status card. "What if the water readings are wrong? Then the alerts are wrong too."

"So we build the readings first and make sure they work," Comet says slowly. "Then add alerts."

Nova blinks her blue eyes. "Great discovery," she says. "And after Lena tries each piece, you can change it."

Wren writes two words on the whiteboard: iterative and incremental.

"Those sound the same," Comet says. Wren smiles. "Look closely. They are not."

Planned or exploratory

A development process can be ordered and intentional, or it can be exploratory.

These phases are commonly used when developing a program: investigating and reflecting, designing, prototyping and testing.

The crew investigated on Tuesday and designed on Wednesday. Prototyping and testing come next.

BEACON'S PHASES SO FAR, IN THE CREW'S ORDER

Tap a card.
Then tap its spot.

1First

2Second

3Third

4Last

Iterative and incremental

An iterative process refines and revises the program based on feedback, testing or reflection, all the way through.

An incremental process breaks the problem into smaller pieces. It makes sure each piece works before adding it to the whole.

Beacon will use both. The crew builds one screen at a time, and changes each one after feedback.

ITERATIVE OR INCREMENTAL?

Read the question.
Tap your answer.

The crew finishes the readings screen, checks it works, and only then starts the alerts screen.

Lena says the buttons are too small, so the crew redraws them and asks her again.

After testing, Wren reflects on what confused users and revises the storyboard.

Prototypes

A prototype is an early version that shows the core function of a product or process.

Prototypes are useful for getting early feedback in the design process.

They can also show whether a product is possible to build at all.

Beacon's paper prototype lets Lena react to the design long before any real code exists.

Working as a team

Pair programming is a common way for developers to collaborate.

Effective teams practice communication, consensus building, conflict resolution and negotiation.

Collaboration that includes diverse perspectives helps avoid bias in the development of computing innovations.

Statement	True or false?
A prototype shows the core function of a product.	?
Prototypes are only useful after the program is finished.	?
Pair programming is a common way to collaborate.	?
A team with diverse perspectives is more likely to build in bias.	?
A development process can be exploratory.	?

WHY THIS EXERCISEGood process and good teamwork catch problems early, when they are easiest to fix.

WHICH TEAM SKILL?

Read the question.
Tap your answer.

Comet and Wren disagree about the alert sound, so each explains a reason and they settle on a quiet chime.

One person writes the plan while the other reads it aloud and checks each line, then they swap.

The whole crew talks until everyone can agree on the three screen names.

On paper, draw a timeline of Beacon's build. Mark each screen being added, and draw a loop arrow wherever feedback leads to a change.

BUILD BEACON INCREMENTALLY

?Test it with Lena and fix what confuses her.
?Test the two screens together.
?Add the Alerts screen.
?Build the Plant Status screen on paper.
?Add the Send to Mission Control screen.

WHY THIS EXERCISEIncremental work means a broken piece is found before it is buried under other pieces.

What do you call a development process that refines and revises based on feedback? Type one word.

WHY THIS EXERCISEIterative development keeps users in the loop all the way through.

An early version that shows the core function is a ____.

Making each small piece work before adding it is ____ development.

Think of something you built or made in steps, like a model, a meal or a project. Was your process iterative, incremental, or both?Comet wanted to build all three screens tonight. Write two sentences explaining to her why one piece at a time is safer.

Sharp thinking. Tomorrow is Impact Friday, where you look at the effects of what we build.