A recipe
Cooks read the steps and get the ingredients ready before they turn on the stove.
10THINK LIKE A PROGRAMMER · PLAN
Plan first, then code.
Write the steps in plain words as # comments. Then turn each one into Python.
IN REAL LIFE
Plans come before doing.
People plan in plain words before they start.
A trip
Before a trip, your family looks at the map and picks the way.
A school project
You write a list: find pictures, glue them, write the title. Then you start.
LOOK FIRST
How to plan a program.
Input, work, output
What comes in? What do you do with it? What comes out?
Plan in # comments
Write each step in plain words after a #. Python skips those lines.
Pick a tool
For each step, choose a box, an if, a loop, or a function.
Pick the tool: keep something → box =. Choose → if. Repeat → loop. Use the same steps many times → function def.
LOOK FIRST
From plan to Python.
Each step of the plan becomes one line of Python.
cookies = 12Plan: keep the number of cookies. Input, so a box.friends = 4Plan: keep the number of friends. Another box.each = cookies // friendsPlan: share them out. The work: // divides into whole cookies.print("Each friend gets", each)Plan: show the answer. The output.RUN IT
A plan with its code.
Guess first. Then run real Python and check.
Guess the result
# Plan: share cookies
# 1. Keep the numbers (input)
cookies = 12
friends = 4
# 2. Share them out (work)
each = cookies // friends
# 3. Show it (output)
print("Each friend gets", each)What will Python show?
OUTPUT
PyBot's hint
Ready. Press Run Python.
Python runs here thanks to Pyodide ♥
Pyodide 314.0.3 runs CPython in your browser with WebAssembly.
Open-source under the Mozilla Public License 2.0. License
Now change one thing: Change friends to 6 and run again. Which step of the plan changed?
YOUR TURN
Plan it, then code it.
Try each tiny question. A wrong answer becomes something to review.
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Like a cook
You want to make pancakes for the first time.
What is the best first step?
A plan line
# 2. Add the pointsWhat does Python do with this line?
Input, work, output
A program: keep your age, add 1, show your age next year.
Which part is the work?
Pick the tool
# If it rains, say:
# take an umbrellaWhich tool fits this step?
Pick the tool again
# Say hi to each
# friend in the listWhich tool fits this step?
Same steps, many places
# Show the game title
# at the start,
# after a win,
# and at the endWhich tool fits this step?
Plan to code
# 3. Show the totalWhich line of Python does this step?
Plan in order
Plan for a program that tells you how many legs 3 dogs have.
Which plan order works?
Turn the plan into code
PyBot wrote the plan, but steps 2 and 3 have no code yet. Write one line under each.
Goal output
Total points: 12OUTPUT
Use the tool from the plan
The plan says to greet each friend, but the code only greets one. Use a loop.
Goal output
Hi Ana Hi Leo Hi MiaOUTPUT
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BIG IDEA
Plan in words, then code.
Find the input, the work, and the output. Write each step as a # comment, then turn it into Python with the right tool.