2.1 Unplugged
In this unplugged lesson, students decompose the chicken dance and realize that the code can be shorter if they use a loop.
CS Concept : Loops
OBJECTIVES:
By the end of this lesson, students will
identify a repeat loop and recognize why it is useful.
TEACHER RESOURCES:
Standards
CSTA 2-AP-12: Design and iteratively develop programs that combine control structures, including nested loops and compound conditionals.
Do Now (5 minutes)
What is a Loop and why is it useful? Slides. Figma
LEARNING GOALS:
Beginning
Some Tasks involve repeating actions
Instructions like “step 3 times” do the same thing as “step, step, step”
Intermediate
Repeating things can have a cumulative effect
Repetitions can go on forever or stop
Different kind of tasks require different kinds of repetition
Unplugged Project ( 45 minutes)
Project the video Chicken Dance and dance. Notice how steps repeat in a dance.
What are the steps for this dance? Try to prompt students to use the word "algorithm" in their replies.
Let's use the key word "Loop" to shorten our algorithm.
e.g Loop 4 times : hands. Have students say what happens next: Loop 4 times: arms. Loop 4: Shake. Loop 4: Clap.
Divide students into groups of two and have them create a very short dance routine, using Dance algorithm handout.
Students create steps for the dance routine. (an algorithm).
Groups swap their dance algorithm and perform each other's dance in front of creators.
They debug any steps that do not work and give feedback on efficiency: Could the other team have used a loop to make a shorter algorithm?
Extra Resource: University of Chicago: Loop Charades Slides. (materials: Loop Charade | Manipulatives | Direction wall signs )
Close-Out (5 minutes)
To-day you made an Algorithm for a Dance. You used a loop, so that your instructions were shorter and easier to read.
What are Algorithms?
Why are Loops helpful?
Do you need to use a loop to make a dance?
Potential Responses
Algorithms are a series of steps or directions to do a task.
Less steps are needed, if you use a loop. Loops allow your algorithm to be shorter which makes it easy to read.
No, there is always more than one way to do a task, but loops will save you time!