1. Repeating Actions

2. What will we learn today?
Repeated Actions
Need for Repetition
Repetition with Loop
Nested Loops

3. Repeated Actions in Real Life
Consider those daily actions
When we talk, we simply open and close our months repeatedly a counted number of times
When we walk, we move our legs forward and backward as we move a counted number of steps

4. Need for Repetition
Consider a situation in which a man walks 5 steps forward towards a palm tree
The man’s legs walk a step with each meter that he moves forward
(if man moves forward 5 meters, his legs walking occur 5 times)
One possible way is to animate 5 steps
But, what if we want to repeat the walking action 20 times
(becomes tedious and boring, isn’t it??)
We can use clipboard. But it will be a bit tedious copying and dragging block of instruction several number of times

5. Repetition with Loops
An easy way to do this is by using a loop statement
The Loop Statement
Is a simple way to repeat an action a counted number of times
Is used to execute a block of instructions again and again (limited number of times)
Is quick and easy to write and also easy to understand
A count is used to describe the number of times a loop/action(s) repeats

6. Hide and Seek Example with Loops
Remember the “hide and seek” example we did in the methods lecture
Remember how many times we had to animate(copy and past) the actions
Painful and tedious wasn’t it!!!
Now, the torture is over and we will use loops to make our lives simpler

7. Repetition with Loop
We have repeated actions in ‘Turn Around’ methods and in the ‘world.myfirst’ method
To create a loop in a program
Drag a loop tile into the editor inside the do-in order block of ‘world.myfirst’ method
Choose other and enter number 3 in the popup menu
Drag the ‘world.seekCat’ method into the loop statement
Inside the do-together block make two loops for the turning around methods
A loop can be executed only a whole number of times

8. Nested Loops
A loop can be nested inside another loop (a loop is placed inside other loop)
Remember, the ‘move around’ method was used to make a complete turn around the tree (which requires repeating the moving a step and turning right actions ten times)
To make 3 complete turns we need to repeat the previous action 3 times
Loop 3 times
Loop 10 times
Move Around

9. Nested Loop The second loop ‘Loop 10 times’ is called a nested loop
It will fully execute each time the outer loop ‘loop 3 times’ executes once
The count of the outer loop is 3, and the count of the inner loop is 10
The inner loop will execute 10 times for each of the 3 executions of the outer loop
The moving around action will occur 30 (3*10) times in total
Loop 10 times
Move Around

10. The Result Loop Statement

11. Turn Around methods with Loops

12. Let’s Work with Alice
Write an animation where an Arabian man in his tent serves coffee to his guests
Create a method ‘fill-inCups’ in which the host man holding the dallah (middle east) and fill-in 3 empty cubs in the tray (loop 3 times)
Create a method ‘serveCoffee’ where the host man serves his guests (loop 2 times)
Develop the animation for this story