BEGIN:
LESSON 12
GOAL: Students will be able to…
- Explain the purpose of a while loop
- Create while loops to repeat code while a condition is true
- Utilize while loops to solve new types of problems
- Test their solutions on different Karel worlds
| Loop | A loop is a way to repeat code in your program. |
| While Loop | Lets us repeat code as long as something is true. |
| Condition | A condition is code that you put inside an if statement or while-loop. |
| Control Structure | A control structure lets us change the flow of the code. |
| Fencepost Problem | A problem when using a while loop where you forget one action at the beginning or the end. |
DO THE FOLLOWING IN ORDER:
- REVIEW:
- Do 1.11.2 If/Else Statements Quiz
- What do we know about for loops?
- In what situation would for loops not be helpful?
- Do Now: Write instructions that will allow me (the teacher) to clap at the same time as walking. Use a conditional statement or for loop if necessary.
- Be prepared to share your instructions with the class.
- I will execute the commands exactly as they are read.
- Introducing the concept of a while loop: we wanted to achieve clapping while we were walking, thus we can use a while loop.
- Watch 1.12.1 While Loops in Karel
- Get a copy of While loops (student-version) and begin working on the activity.
- After you have completed the activity in the handout, how would a for loop would be written for the activity? How reusable would our code be if Karel’s world became a 4×2 world, or a 5×5 world?
It is important to remember about writing reusable code, so that if Karel’s world changed, how useful would a for loop be if Karel’s world decreased to 4×2 or a 5×5?
- After you have completed the activity in the handout, how would a for loop would be written for the activity? How reusable would our code be if Karel’s world became a 4×2 world, or a 5×5 world?
- 1.12.3 Move to Wall demonstrates this concept by changing Karel’s world from 6×6, to a 8×8 and 10×10.
- Go over the Why Use Loops? handout–get it from your teacher.
- SHOW ME WHEN YOU ARE DONE: Work individually or in pairs to complete:
- 1.12.4 Follow The Yellow Ball Road
- 1.12.5 Lay Row of Tennis Balls: Get the Fence Post Handout from your teacher to possibly help you
- 1.12.6 Big Tower
- Be sure to use debugging strategies so that your code is reusable in all of Karel’s worlds.
- FYI: CodeHS Online Textbook–use this as a resource
- BEFORE YOU LEAVE, WRITE ABOUT THE FOLLOWING in the Word Online file named Web Apps & Coding for this class (you will write in this file daily):
- What is the difference between for loops and while loops?
- Provide an example of when you would use each loop.