9_3_3
WHAT: Understand the difference between definite and indefinite iterations
HOW:
Activity 1 - READ
Definite - we know how many times a loop will run before it starts.
Indefinite - we don't know how many times a loop will run until it is finished.
The two loops that we use in Python are a for loop and a while loop. Which one is definite and which is indefinite?
Below is some pseudocode for each type of loop to help you answer:
For loop
FOR i in 1 TO 5
OUTPUT i
While loop
WHILE i != 5
OUTPUT i
INPUT i
When we write a for loop, we know how many times it will loop before it starts. This means that a for loop is a definite loop.
When we write a while loop, we are testing a condition. That loop will run for as long as the condition is true. We don't necessarily know when the condition will become false so it is an indefinite loop.
Activity 2 - Re-visit
You should be really familiar with for loops and while loops at this point. If you aren't then watch these videos again:
CHECK:
EMBED:
- Write a for loop that will display the alphabet.
- Write a while loop that will display the alphabet.
- Which one is more efficient?
- Based on your knowledge of definite and indefinite loops, which one SHOULD you use the display the alphabet?
CLASSROOM IDEAS:
This lesson is basically a re-cap with some know keywords for the students to learn. If they are finding this concept a struggle then it may be a good idea to pause here and refresh those coding skills.