Comments that explain and justify data and code structures

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which comment best justifies a choice of data structure?

A # this is an array

B # array used because the size is fixed at 30 students

2. Which comment best describes the purpose of the variable totalMarks?

A # totalMarks holds the running sum of all test marks for the class average

B # totalMarks equals 0

3. Which comment avoids simply repeating the code? count = count + 1

A # count tracks how many students passed

B # add 1 to count

4. Which comment best explains why a loop is used?

A # loop through every mark so each one is added to the total

B # for loop

5. Which comment best justifies using a record for a student?

A # student record

B # record used because name, age and mark are different data types

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1# total holds the running sum of all marks		A# loop through every mark to find the highest for mark in marks:
2# list used because the number of students can change		BA comment describing a variable's purpose: what the variable is for
3A comment that explains why a loop is used and what it achieves		CThe comment only repeats what the code does and does not explain what count is for. Better: # count tracks how many students passed
4A comment that justifies using a record to group related data of different types		DThe comment names the structure but gives no reason for choosing it. Better: # array used because the size is fixed at 30 students
5# set count to 0 count = 0		E# record used to keep one student's name, age and mark together student = {"name": "Ava", "age": 16, "mark": 88}
6# this is an array scores = [0] * 30		FA comment justifying the choice of data structure by giving the reason it was chosen

Definitions

# array used because size is fixed

Fill in the Blanks

Complete each line of code by filling in the missing parts.

_ total of all marks, used to find the average total = 0

# loop runs once for each of the 30 students ___ i in range(30): marks.append(0)

# dictionary used so marks are found by name marks = __

# repeat until a valid mark is entered _____ mark < 0 or mark > 100: mark = int(input("Mark: "))

# list used because the size is fixed at 30 names = [""] _ 30

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A # fixed size: 30 students

B marks = [0] * 30

C total = 0

D // total: sum used for average

E for m in marks: total += m

Question 2

A # array: 5 days, size fixed

B temps = [0] * 7

C for d in range(7):

D temps[d] = d + 20

Question 3

A students = []

B students.append("Mia")

C # array used: size is fixed

D print(len(students))

Question 4

A tests = 5

B for i in range(tests):

C # for i in range(tests)

D print(i + 1)

Question 5

A mark = 72

B # pass mark is 50 or more

C if mark >= 60:

D print("Pass")

Answer Key

Comments that explain and justify data and code structures

Section A: Quick Questions

B — # array used because the size is fixed at 30 students

A — # totalMarks holds the running sum of all test marks for the class average

A — # count tracks how many students passed

A — # loop through every mark so each one is added to the total

B — # record used because name, age and mark are different data types

Section B: Match the Pairs

# total holds the running sum of all marks → A comment describing a variable's purpose: what the variable is for

# list used because the number of students can change → A comment justifying the choice of data structure by giving the reason it was chosen

A comment that explains why a loop is used and what it achieves → # loop through every mark to find the highest for mark in marks:

A comment that justifies using a record to group related data of different types → # record used to keep one student's name, age and mark together student = {"name": "Ava", "age": 16, "mark": 88}

# set count to 0 count = 0 → The comment only repeats what the code does and does not explain what count is for. Better: # count tracks how many students passed

# this is an array scores = [0] * 30 → The comment names the structure but gives no reason for choosing it. Better: # array used because the size is fixed at 30 students

Section C: Definitions

# array used because size is fixed — A comment that explains what a variable, array, record or algorithm is for and why it was chosen, rather than just repeating what the code does.

Section D: Fill in the Blanks

#
 total of all marks, used to find the average
total = 0

# loop runs once for each of the 30 students
for i in range(30):
    marks.append(0)

# dictionary used so marks are found by name
marks = {}

# repeat until a valid mark is entered
while mark < 0 or mark > 100:
    mark = int(input("Mark: "))

# list used because the size is fixed at 30
names = [""] * 30

Section E: Spot the Error

D — Python comments start with #, not //. The // line is invalid code and causes a syntax error. It should be '# total: sum used for average'.

A — The comment gives the wrong reason for the array's size. The code creates 7 elements, so the comment must say 7 days. A comment that contradicts the code misleads the next programmer.

C — The comment justifies the structure with the wrong reason. The code uses append(), so the size grows. It should say the list was chosen because its size can change.

C — This comment only repeats the code. A good comment explains why the loop exists, such as '# loop: one pass per test'.

C — The comment says the pass mark is 50, but the condition tests for 60. The code and its explanation must agree, so the condition should be mark >= 50.