Day 8: Iteration (Loops) - Part 1

Learning Objectives

• AAP-2.H: For iteration: Write iteration statements.
• AAP-2.I: For iteration: Determine the result or side effect of iteration statements.
• AAP-2.J: Express an algorithm that uses iteration without using a programming language.

Essential Questions

• How do programs repeat actions efficiently?
• How can we use count-controlled loops to process data or perform repeated tasks?

Materials Needed

• Presentation slides on iteration and for loops
• Programming environment
• Loop tracing worksheets
• Sample data sets for processing
• Exit ticket templates

Vocabulary

• Iteration
• Loop
• Count-controlled loop
• For loop
• Counter variable
• Iteration variable
• Loop body
• Repetition

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review Boolean logic and compound conditions from previous lesson
   • Connect to today's focus on repeating actions with loops

2. Warm-up Activity (5 minutes)

   • Present a task that requires repetition (e.g., adding numbers 1 through 10)
   • Ask students to write out the steps to complete this task without loops
   • Discuss the inefficiency of writing repetitive code

Main Activities (32 minutes)

3. Lecture: Introduction to Iteration (12 minutes)

   • Define iteration as a programming construct that repeats a set of statements
   • Explain the importance of loops for efficiency and code readability
   • Introduce count-controlled loops (for loops):
     • Structure and syntax: REPEAT n TIMES
     • How the loop counter works
     • Execution flow in a loop
     • When to use count-controlled loops
   • Demonstrate how loops execute step by step
   • Explain common patterns and use cases for for loops:
     • Repeating an action a specific number of times
     • Processing items in a sequence
     • Generating sequences or patterns
   • Discuss the concept of the loop body and loop control

4. Demo: Count-controlled Loops (For Loops) (8 minutes)

   • Walk through examples of programs with for loops:
     • Summing numbers from 1 to n
     • Printing patterns
     • Performing calculations multiple times
   • Show how to trace the execution of loops step by step
   • Demonstrate how the loop counter changes with each iteration
   • Highlight common patterns and techniques with for loops
   • Show how to use the loop counter within the loop body

5. Hands-on: Implementing For Loops in Code (12 minutes)

   • Students work in the programming environment
   • Guide students through creating programs with for loops
   • Have students implement programs for scenarios like:
     • Calculating factorial of a number
     • Generating multiplication tables
     • Creating patterns of symbols
     • Computing sums or averages
   • Encourage students to trace their loops manually to understand execution flow

Closing (10 minutes)

6. Activity: Using Loops to Process Collections of Data (5 minutes)

   • Provide students with a simple data set (e.g., list of numbers)
   • Students write a loop to process the data (find sum, average, maximum, etc.)
   • Share and discuss different approaches
   • Highlight how loops make data processing efficient

7. Exit Ticket and Preview (5 minutes)

   • Students write programs that use for loops to solve problems
   • Preview that next class will focus on condition-controlled loops (while loops)

Assessment

• Formative: Quality of loop implementation during hands-on activities
• Exit Ticket: Correctness and efficiency of programs using for loops

Differentiation

For Advanced Students

• Provide more complex looping challenges
• Introduce nested loops concept
• Challenge them to optimize loop-based solutions

For Struggling Students

• Offer more structured templates for loops
• Provide step-by-step tracing guides
• Focus on simpler loop patterns before moving to complex ones

Homework/Extension

• Complete a worksheet with for loop exercises
• Create a program that uses loops to generate interesting patterns
• Research how loops are used in animations or simulations

Teacher Notes

• Emphasize that loops are one of the fundamental programming constructs
• Watch for off-by-one errors in loop boundaries
• Make connections to mathematical sequences and series
• Consider using physical demonstrations to show repetition
• Remind students that understanding loops is essential for efficient programming