Week 04 · Monday: Choices in a loop (Code Crew G4)

Monday: True or False?

An alarm beeps in the storeroom. "Water is low!" Rocket says. "Let's build a program that warns us next time."

Raven floats to the shelf and counts three water tanks. "What do you notice?" she asks. "Low is just a feeling. A program needs a rule. Is three low? Is five low?"

Rocket scratches his head. Nova projects a number line in the air, with a glowing mark at five. "Would you like a hint? Python can compare two numbers and answer True or False."

Comparisons give True or False

A comparison asks a question about two values. Python answers with True or False. These answers are called Booleans.

water = 3
print(water < 5)
print(water > 5)
print(water == 3)
print(water != 3)

The screen shows
True
False
True
False

Sign	Question it asks	Example	Answer
<	is it less than?	3 < 5	True
>	is it greater than?	3 > 5	False
<=	is it less than or equal to?	5 <= 5	True
>=	is it greater than or equal to?	4 >= 5	False
==	is it the same?	3 == 3	True
!=	is it different?	3 != 3	False

Strings can be compared too. "oats" == "Oats" is False, because a small o and a big O are different letters.

Comparison	Does Python say True?
8 > 5	?
4 >= 4	?
3 != 3	?
10 < 2	?
"tape" == "Tape"	?

WHY THIS EXERCISEEvery if in a program depends on a comparison like these.

x = 7
print(x <= 6)

What does the program above show?

WHY THIS EXERCISEPython prints a Boolean as the word True or False.

PICK THE COMPARISON

Read the question.
Tap your answer.

A tank is full when it holds 10 or more units. Which comparison checks that?

Which comparison checks that the hatch is not "closed"?

Try it

Say a comparison out loud, like 6 is greater than 2.
Your grown-up answers True or False. Then swap.

Practice lab: check the oxygen

oxygen = 9
print(oxygen > 10)
print(oxygen <= 9)
print(oxygen != 4)
print("Dock" == "dock")

What does line 2 show?

What does line 3 show?

What does line 4 show?

What does line 5 show?

SIGNS AND ANSWERS

Read the question.
Tap your answer.

Which sign asks: is it different?

What does print(6 >= 6) show?

A shelf is low when it holds fewer than 3. Which check says True for a low shelf?

Comparison	Does Python say True?
2 < 9	?
9 <= 8	?
"Go" != "go"	?
5 > 5	?

WHY THIS EXERCISEStrings compare letter by letter, so a capital letter makes them different.

x = 12 runs. What does print(x > 10) show?

WHY THIS EXERCISEPython prints the Boolean as the word True or False.

Write three comparisons that use the signs <, >= and !=. Write True or False after each one.

Nice work! You can read every comparison sign. Tomorrow your loops will use them to make choices.