Unit 9: Toolboxes
Borrowing code others wrote.
Unit 9 of 31 in Python for kids. Its 5 lessons are Borrowing Tools, The Maths Toolbox, Dates, Counting Days and Toolbox Master — below is everything each one explains, and a question or two from it to try.
Every sample on this page was run through real Python before it shipped, and prints exactly what it says it prints.
This unit opens with a fortnight’s trial of everything — no card needed — or with a family plan, bought in the iPhone app. The first two units of every track are free for ever. Try it in the app.
🧰 Borrowing Tools
You do not have to write everything
A module is a box of code somebody already wrote. import opens the box, and then you reach inside it with a dot.
Python
import math
print(math.sqrt(9))It prints
3.0
Taking just one tool out
from ... import ... lifts one thing out of the box, so you can use its name on its own — no dot needed.
Python
from math import sqrt
print(sqrt(25))It prints
5.0
Giving the box a shorter name
as renames it for the rest of your program. Handy when the real name is long.
Python
import random as r
r.seed(1)
print(r.randint(1, 6))It prints
2
Try it yourself
What does the dot in math.sqrt mean?
- Multiply
- Look inside the math box for the thing called sqrt
- End of the line
- A decimal point
Where should your imports go?
- At the very top of the file
- At the bottom
- Inside every function
- Anywhere, it makes no difference to a reader
Answer them in the app
📐 The Maths Toolbox
Rounding your own way
floor always goes down, ceil always goes up. round goes to whichever is nearer.
Python
import math
print(math.floor(4.8))
print(math.ceil(4.1))
print(round(4.5))It prints
4 5 4
Python rounds .5 to the even one
That is not a bug. Always rounding .5 upwards would slowly push every average too high, so Python picks the even neighbour instead. round(4.5) is 4 and round(5.5) is 6.
Python
print(round(4.5))
print(round(5.5))
print(round(2.675, 2))It prints
4 6 2.67
Pi and powers
math.pi is a number, not a function, so it needs no brackets. ** does powers just fine on its own.
Python
import math
print(round(math.pi, 4))
print(2 ** 10)It prints
3.1416 1024
Try it yourself
What does this print?
Python
import math
print(math.floor(7.9))
print(math.ceil(7.1))Why does math.sqrt(16) print 4.0 rather than 4?
- It is a mistake
- sqrt always answers with a decimal number
- 16 is a decimal
- Because of the import
Answer them in the app
📅 Dates
A date is a thing you can hold
The datetime module has a date you can build from a year, month and day — and then ask it questions.
Python
from datetime import date
party = date(2026, 12, 25)
print(party)
print(party.year)
print(party.month)It prints
2026-12-25 2026 12
What day of the week was it?
strftime turns a date into text however you like. %A is the weekday name, %d the day, %B the month name, %Y the year.
Python
from datetime import date
d = date(2026, 8, 7)
print(d.strftime("%A"))
print(d.strftime("%d %B %Y"))It prints
Friday 07 August 2026
Try it yourself
What does this print?
Python
from datetime import date
d = date(2026, 8, 7)
print(d.day)In strftime, what does %A give you?
- The year
- The name of the weekday
- The month number
- A capital A
Answer them in the app
⏳ Counting Days
How many sleeps?
Take one date away from another and you get a timedelta — a length of time. Ask it for .days.
Python
from datetime import date
today = date(2026, 8, 7)
party = date(2026, 12, 25)
print((party - today).days)It prints
140
Jumping forwards
Add a timedelta to a date to move through the calendar. It handles months and leap years for you.
Python
from datetime import date, timedelta
d = date(2026, 2, 26)
print(d + timedelta(days=3))It prints
2026-03-01
Try it yourself
What does this print?
Python
from datetime import date, timedelta
d = date(2026, 8, 7)
print(d + timedelta(days=7))Why do you write .days at the end?
- To make it print nicely
- Subtracting gives a length of time, and .days asks that length how many days it is
- It is optional
- To turn it into a date
Answer them in the app
🏆 Toolbox Master
Try it yourself
What does this print?
Python
import math
print(math.ceil(2.1) + math.floor(2.9))Answer it in the app