Sequence: instructions run in order
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. In a program using sequence, which statement runs first?
2. What does this code print?
x = 5
x = x + 2
print(x)
3. What does this code print?
x = 4
print(x)
x = 9
4. Two lines are swapped:
A: total = 10, then print(total)
B: print(total), then total = 10
Which version runs without a NameError?
5. True or false: swapping two statements in a sequence can change the result of a program.
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1x = 5 x = x + 2 print(x) | ACauses an error because total is used before it is given a value | |
| 2print(total) total = 10 | BThe output statement is placed before the calculation, so area has no value when it is printed. Move the calculation above print. | |
| 3Swapping two statements can change the output, because each line runs in order | CRuns top to bottom and prints 7, because x is changed before it is printed | |
| 4A simple input-process-output program follows sequence: input first, then process, then output | Da = 3 a = a * 2 print(a) # prints 6 | |
| 5print(area) area = width * height | EThe update comes after print, so the output shows 10 instead of 15. Put the update before print. | |
| 6score = 10 print(score) score = score + 5 | Fn = int(input()) double = n * 2 print(double) |
C
Definitions
sequence
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
name = input("Name: ")
print("Hi " + ____)
2.
total = 10
total = total + 5
print(_____)
3.
age = ___(input("Age: "))
print(age + 1)
4.
count = 1
count = count _ 1
print(count)
5.
print("Start")
_____("Middle")
print("End")
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
score = 10
B
score = score + 5
C
print(total)
Question 2
A
width = 4
B
height = area / width
C
area = width * height
D
print(area)
Question 3
A
x = x + 2
B
x = x * 3
C
print(x)
Question 4
A
n = 3
B
n = n + 2
C
n = n * 2
D
print n
Question 5
A
age = input('Age: ')
B
nxt = age + 1
C
print(nxt)
Answer Key
Sequence: instructions run in order
Section A: Quick Questions
Q1
B — The top statement runs first, then the next one down
Q2
A — 7
Q3
A — 4
Q4
A — A: total = 10, then print(total)
Q5
B — True
Section B: Match the Pairs
Q1
x = 5
x = x + 2
print(x) → Runs top to bottom and prints 7, because x is changed before it is printed
Q2
print(total)
total = 10 → Causes an error because total is used before it is given a value
Q3
Swapping two statements can change the output, because each line runs in order → a = 3
a = a * 2
print(a) # prints 6
Q4
A simple input-process-output program follows sequence: input first, then process, then output → n = int(input())
double = n * 2
print(double)
Q5
print(area)
area = width * height → The output statement is placed before the calculation, so area has no value when it is printed. Move the calculation above print.
Q6
score = 10
print(score)
score = score + 5 → The update comes after print, so the output shows 10 instead of 15. Put the update before print.
Section C: Definitions
Q1
sequence — A control structure where statements run one after another, top to bottom, so changing their order can change the result.Section D: Fill in the Blanks
Q1
name = input("Name: ")
print("Hi " + name)Q2
total = 10
total = total + 5
print(total)Q3
age = int(input("Age: "))
print(age + 1)Q4
count = 1
count = count + 1
print(count)Q5
print("Start")
print("Middle")
print("End")Section E: Spot the Error
Q1
C — The variable total was never created. The statements run in order and the value is stored in score, so the last line should be print(score).
Q2
B — This line uses area before it exists. area is only created on line 3, and Python runs the lines top to bottom. It should be height = 3.
Q3
A — This is the first statement, so x has no value yet and Python raises a NameError. The program must start by giving x a value, x = 2.
Q4
D — In Python 3, print is a function and needs brackets. The last statement should be print(n), which outputs 10 after the three lines run in order.
Q5
B — input() gives a string, so adding 1 to it causes a TypeError. The process step must convert it first: nxt = int(age) + 1.