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Can't Stop Dancing

Experience: 1st year, 1st quarter
Practice: Testing and refining computational artifacts and Communicating about computing
Concept: Algorithms and Control
Length: 50+

Overview and Purpose

Coders use the repeat block to repeat a silly dance for Scratch Cat using motion blocks. The purpose of this project is to introduce young coders to repeating algorithmic sequences in ScratchJr.

Lesson plan Youtube logo

Overview video

Objectives and Standards

Process objective(s):

Statement:

I will learn how to use repeat blocks and parameters to create algorithms that repeat.

Question:

How can we use repeat blocks and parameters to repeat algorithms?

Product objective(s):

Statement:

I will create an algorithm that makes Scratch Cat repeat a dance sequence using motion blocks and repeat blocks.

Question:

How can we use motion blocks and repeat blocks to make Scratch Cat repeat a dance algorithm?

Main standard(s):

1A-AP-10 Develop programs with sequences and simple loops, to express ideas or address a problem.

Programming is used as a tool to create products that reflect a wide range of interests. Control structures specify the order in which instructions are executed within a program. Sequences are the order of instructions in a program. For example, if dialogue is not sequenced correctly when programming a simple animated story, the story will not make sense. If the commands to program a robot are not in the correct order, the robot will not complete the task desired. Loops allow for the repetition of a sequence of code multiple times. For example, in a program to show the life cycle of a butterfly, a loop could be combined with move commands to allow continual but controlled movement of the character. (source)

Reinforced standard(s):

1A-AP-08 Model daily processes by creating and following algorithms (sets of step-by-step instructions) to complete tasks.

Composition is the combination of smaller tasks into more complex tasks. Students could create and follow algorithms for making simple foods, brushing their teeth, getting ready for school, participating in clean-up time. (source)

1A-AP-11 Decompose (break down) the steps needed to solve a problem into a precise sequence of instructions.

Decomposition is the act of breaking down tasks into simpler tasks. Students could break down the steps needed to make a peanut butter and jelly sandwich, to brush their teeth, to draw a shape, to move a character across the screen, or to solve a level of a coding app. (source)

1A-AP-14 Debug (identify and fix) errors in an algorithm or program that includes sequences and simple loops.

Algorithms or programs may not always work correctly. Students should be able to use various strategies, such as changing the sequence of the steps, following the algorithm in a step-by-step manner, or trial and error to fix problems in algorithms and programs. (source)

1A-AP-15 Using correct terminology, describe steps taken and choices made during the iterative process of program development.

At this stage, students should be able to talk or write about the goals and expected outcomes of the programs they create and the choices that they made when creating programs. This could be done using coding journals, discussions with a teacher, class presentations, or blogs. (source)

Practices and Concepts

Main practice(s):

Practice 6: Testing and refining computational artifacts

"Testing and refinement is the deliberate and iterative process of improving a computational artifact. This process includes debugging (identifying and fixing errors) and comparing actual outcomes to intended outcomes. Students also respond to the changing needs and expectations of end users and improve the performance, reliability, usability, and accessibility of artifacts." (p. 81)
P6.1. Systematically test computational artifacts by considering all scenarios and using test cases." (p. 81)

Reinforced practice(s):

Practice 7: Communicating about computing

"Communication involves personal expression and exchanging ideas with others. In computer science, students communicate with diverse audiences about the use and effects of computation and the appropriateness of computational choices. Students write clear comments, document their work, and communicate their ideas through multiple forms of media. Clear communication includes using precise language and carefully considering possible audiences." (p. 82)
P7.2. Describe, justify, and document computational processes and solutions using appropriate terminology consistent with the intended audience and purpose. (p. 82)

Main concept(s):

Control

"Control structures specify the order in which instructions are executed within an algorithm or program. In early grades, students learn about sequential execution and simple control structures. As they progress, students expand their understanding to combinations of structures that support complex execution." (p. 91)
Grade 2 - "Computers follow precise sequences of instructions that automate tasks. Program execution can also be nonsequential by repeating patterns of instructions and using events to initiate instructions." (p. 96)

Reinforced concept(s):

Algorithms

"Algorithms are designed to be carried out by both humans and computers. In early grades, students learn about age-appropriate algorithms from the real world. As they progress, students learn about the development, combination, and decomposition of algorithms, as well as the evaluation of competing algorithms." (p. 91)
Grade 2 - People follow and create processes as part of daily life. Many of these processes can be expressed as algorithms that computers can follow." (p. 96)

ScratchJr Blocks

Vocabulary

Algorithm

A step-by-step process to complete a task. (source)
A formula or set of steps for solving a particular problem. To be an algorithm, a set of rules must be unambiguous and have a clear stopping point. (source)

Code

Any set of instructions expressed in a programming language. (source)
Written computer instructions. The term code is somewhat colloquial. For example, a programmer might say: "I wrote a lot of code this morning" or "There's one piece of code that doesn't work." Code can appear in a variety of forms. The code that a programmer writes is called source code. After it has been compiled, it is called object code. Code that is ready to run is called executable code or machine code. (source)

Loop

A programming structure that repeats a sequence of instructions as long as a specific condition is true. (source)
In a loop structure, the program asks a question, and if the answer requires an action, it is performed and the original question is asked again until the answer is such that the action is no longer required. For example, a program written to compute a company’s weekly payroll for each individual employee will begin by computing the wages of one employee and continue performing that action in a loop until there are no more employee wages to be computed, and only then will the program move on to its next action. Each pass through the loop is called an iteration. (source)
The computational concept of running the same sequence multiple times. (source)

Parameter

A specific piece of information used as input each time a process is run; for example, when a person presses a vending machine button for an item, the information for the item location is sent as a parameter so the machine knows what food to dispense. (Thank you, Peter Rich, for the great example)
A special kind of variable used in a procedure to refer to one of the pieces of data received as input by the procedure. (source)
In programming, the term parameter is synonymous with argument, a value that is passed to a routine. (source)

More vocabulary words from CSTA

Click here for more vocabulary words and definitions created by the Computer Science Teachers Association