A recipe that says "cook until done"
A recipe that says "cook until done" is no help if you have never cooked.
You send your design to a builder you have never met. You are away. They cannot ask you anything.
If a step says "check the booking", the builder must guess how. If a step says "if the hour is before 9, output Closed", the builder knows.
A good design can be built by a stranger.
Key words
| Word | What it means | Example |
|---|---|---|
| Sequence | Steps done one after another, in order. | ask, check, save |
| Selection | A choice. The path depends on a yes or no answer. | if the hour is 21, refuse |
| Iteration | Doing steps again and again. | for each hour from 9 to 20 |
| Loop | Code or a flowchart path that repeats steps. | while hour <= 20 (<= means 20 or less) |
| Flowchart | A diagram of steps with arrows. | start, check, book |
| Reusable component | A part you write once and use in many places. | price_for() |
| Sub-system | One big part of the whole solution. | prices, storage, screen |
| Naming convention | A rule for how names are written, used the same way everywhere. | small letters with _ between words, like book_court |
| Third party | A person outside your team, such as a builder who gets your design. | another developer |
| Audience | The people who read your design. | the manager, the builder |
The cells students fill in are left blank in this preview.
The three building blocks of every algorithm
| Construct | Flowchart shape | Hillside example | Python |
|---|---|---|---|
| Sequence | Boxes joined by arrows | Input the hour, then input the court, then save | Lines one after another |
| Selection | A diamond with yes and no | Is the hour from 9 to 20? | if ... else |
| Iteration | An arrow that goes back up | Do this for every hour from 9 to 20 | for or while |
The cells students fill in are left blank in this preview.
Which building block is it?
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Which building block is it?
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Try it: the same loop in Python
names = {10: "Sam", 12: "Aisha"}
hour = 9
while hour <= 20:
if hour in names:
print(hour, names[hour])
else:
print(hour, "free")
hour = hour + 1
# The arrow going back up is the while line.
# <= means "is less than or equal to".
# Change 20 to 12 and run it again.
Quick check: building blocks
Have a go
Quick check: building blocks
4 questionsHave a go: your answers are marked here and then forgotten. Sign in if you would like your score kept, and to pick up where you left off.Sign in to keep your score
Your answers are marked here and are not kept. A college account keeps every student’s marks.