Add to it
score += 1 means the same as score = score + 1.
02CHANGE + MATH
A box can change.
A box can take its own value, change it, and keep the new one. That is how games count points.
USE THE OLD VALUE
Read the right side first.
score = score + 1 looks strange. Python first works out the right side: the old score plus 1. Then it puts the answer back in the same box.
score = 3→score = score + 1→score4
3 + 1 is 4. Now the box keeps 4.
THE SHORT WAY
+= adds to the box.
Take away
lives -= 1 takes one life away from the box.
Start again
score = 0 throws the old value away and puts in 0.
MATH WITH BOXES
Boxes can do math together.
apples = 4 and pears = 3. Python opens both boxes and uses the numbers inside.
Add
apples + pears is 7.
Subtract
apples - pears is 1.
Multiply
apples * 2 is 8. The star means times.
Divide
apples / 2 is 2.0. Dividing always gives a decimal.
JOIN TEXT
+ glues text together.
Let's go slowly, one small step at a time.
Text lives inside quotes
Quotes tell Python: this is text, keep it just as it is.
"cat""Hi""Ana"+ glues two pieces
Python puts the second piece right after the first one, like train cars.
"sun"+"flower"→"sunflower"Python does not add spaces
You choose the space. Put it inside the quotes.
"Hi"+"Ana"→HiAnaStuck together!"Hi␣"+"Ana"→Hi AnaNow there is a space.A box can join too
name has no quotes, so Python opens the box and uses what is inside.
name"Ana""Hi␣"+name→Hi AnaPython opens the boxQuotes change everything
Same + sign, different job.
TEXT: + glues"2"+"3"→"23"NUMBERS: + adds2+3→5
RUN IT
Count PyBot's stars.
Guess first. Then run real Python and check.
Guess the result
score = 3
score = score + 1
print(score)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 + 1 to + 10. Then try the short way: score += 10.
YOUR TURN
Change the boxes.
Try each tiny question. A wrong answer becomes something to review.
0Completed
10Not tried
0Review
Add to the box
stars = 5
stars = stars + 2
print(stars)What will Python show?
The short way
coins = coins + 1Which line does the same job?
Lose a life
lives = 3
lives -= 1
print(lives)What will Python show?
Triple the steps
steps = 2
steps = steps * 3
print(steps)What will Python show?
Two boxes, one answer
apples = 4
pears = 3
print(apples + pears)What will Python show?
Say hello
name = "Ana"
print("Hi " + name)What will Python show?
Where is the space?
print("Hi" + "Ana")What will Python show?
Numbers in quotes
print("2" + "3")What will Python show?
Fix PyBot's code
PyBot found a star, but its score is still 0. Fix the middle line so the box keeps the new score.
Goal output
1OUTPUT
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BIG IDEA
A box can use its old value to make a new one.
score = score + 1 adds one. Next, PyBot meets every math sign.