Check your understanding of the previous reading: the parts of a for loop, the iteration variable, and how a loop runs.

Question 1

Identify each of the components of the for loop:

Two lines of code under `grades = [..., 50, 80]`: `for item in grades:` and an indented `print(item)`, with six numbered labels: 1 points at `for`, 2 at `item`, 3 at `in`, 4 at the indented line, 5 at the end of `grades:`, and 6 at `item` inside `print(item)`.

Label	Points at	Component
1	for
2	item
3	in
4	print(item)
5	grades:
6	item inside print(item)

Question 2

Type the character used at the end of the first line of a for loop.

Show worked solution

The first line of a for loop ends with a colon, as in for item in grades:. The answer is :.

Question 3

What is the type of the Iteration Variable in this code?

groceries = ["Apples", "Cookies", "Steaks"]
for grocery in groceries:
    print(grocery)

Select one answer, then check.

List
Not quite. groceries is the list; the iteration variable grocery holds one element of it at a time.
String
Correct. Each element of groceries is a string, and the iteration variable takes on one element at a time, so grocery is a string.
Integer
Not quite. There are no numbers in the list; its elements are strings like "Apples".
None
Not quite. On every pass the iteration variable holds a real value from the list: one of the strings.

Question 4

Mark each of the following statements about for loops that are true:

Select every answer that applies, then check.

The body of a for loop will have one statement for each element of the iteration list.
Not true. The body can hold any number of statements; the whole body runs once for each element.
for Loops and Functions are basically the same thing
Not true. A function packages code that you call by name; a for loop repeats its body once for each element of a list.
The Iteration Variable will take on each value of the List Variable, one at a time.
True. Each time the loop executes, the iteration variable gets set to the next value from the list.
for Loops always execute the body four times, which is where they get their name.
Not true. The body runs once for each element, however many elements the list has.
Like an if statement and a Function Call, the for Loop might cause the execution to not follow the order of lines.
True. After the last line of the body, execution jumps back up to the for line for the next element.

Question 5

Trace the values of this code. If a variable is not yet defined, put an "X" (without quotes).

grades = [10, 20]
total = 0
for grade in grades:
    adjusted = grade + 10
    total = total + adjusted

Each row is one step: the line that just ran, and the value of every variable after it.

step	line	grades	grade	adjusted	total
1	1	[10, 20]	X	X	X
2	2	[10, 20]		X
3	3	[10, 20]		X
4	4	[10, 20]		20
5		[10, 20]
6
7		[10, 20]
8		[10, 20]			50