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Variables

3-5 Computer Science Modules Series

A subconcept of

Algorithms and Programming

Standard 3.AP.V.1: Create programs that use variables to store and modify data.

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Overview of the Lesson

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What Real-World Problem Does the Standard Address?

Here is an image showing the manager of a shoe store arranging her inventory. There are sure to be many pieces of information she would want to collect in her job. Some of those might include the following:

Total number of shoes sold on a given day
Dollar value of sales for a month
Number of shoes sold of each size
Number of hours employees work in a week
Day of the week with the highest sales
Employee with the highest sales commission
Name and phone number of each employee
Whether or not a particular shoe is in stock

The list could go on and on. As you look at the image and ponder, write a list of other pieces of information the manager might want to collect. Where and how could she keep all this data? How easy would it be for her to get both historical data and current data?

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Your Turn

Write a list of at least three other pieces of information the manager might want to collect.
What options does she have for storing all this data, and how easily can she retrieve both historical and real-time data?
How is the image and list connected to this computer science standard?

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What Does the Standard Say?

In this section you will examine the standard and think about the learning targets and potential ways of measuring student understanding of the concept by addressing the session question, "What does the standard say?"

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Deconstructing the Standard

Examine how a colleague would interpret the parts of the standard for a student or parent. As you read, think about how you would help a parent interpret the standard language, if you would use the same common understandings, and why it would be important to interpret the standard.

Standard: 3.AP.V.1 Create programs that use variables to store and modify data.
Standard Language	Common Understanding
program	This is a set of instructions through which a computer works. When it is run, a program performs the specific task that the programmer has set for it. As humans, we essentially program everything we do by running a set of instructions through our internal computers--our brains. These sets of instructions can take the form of sequences, events, loops, and conditionals.
variables	Variables are simply placeholders for bits of information. They are symbolic names that are used to keep track of values. Those values can change while a program is running. Variables can take on the values of numbers, text, whole sentences, or logical values. Almost everything in life could be distilled to some kind of variable. A person's age could be a number variable. A child's name could be a text variable. A person's sleep state could be a logical value, taking on a value of true if asleep and false if awake.

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The Embedded Content of the Standard

Let's say you are a basketball statistician. There would be many different stats for all the players and for the whole team that you would be tasked with recording, calculating, and reporting. You would probably have a scorebook to keep them in, so in a way, that scorebook was created by someone like a program is created to keep track of many pieces of information, or data.

One major data point you would be sure to keep is a player's score. We can think of the score for each player as a separate variable. At the beginning of the game, that score is automatically known to be zero. Each time a player scores, the points earned are added. In this way, the old stored value of the player's score is modified by adding the earned points to come up with a new score, which then becomes the new stored value of that player's score for the game. At the end of the game, whatever value is stored as that score becomes the player's final score.

In addition, the player's season score would certainly be an item of interest. By taking the stored value of the scores for each game, you could easily add them together to find the season score, which would be another variable itself.

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The Embedded Content of the Standard

In the basketball analogy, you could write a computer program to track the information. You might start by listing out some of the variables in a chart like the one below. The data types could be numbers, text, whole sentences (strings), or logical values (true or false). Of course, there would be many, many more data points.

Variable Name	Data Type	Example
Rebounds	Number	12
Fouls	Number	2
Player_First_Name	Text	Jamie
Player_Last_Name	Text	Williams
Player_Strength	String	Reliable 3-point shooter
Starter	Logical	true

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Achieving the Standard

Learning Targets (Student Friendly Language)	Assessment Targets (Student Evidence)
Standard: Standard: 3.AP.V.1 Create programs that use variables to store and modify data.
I can use variables in my programs to perform mathematical operations.	Students know how to use variables in programs they code to perform mathematical operations, such as adding to the score of a game or subtracting from the number of lives available in a game or using a variable as a countdown timer.

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Your Turn

With respect to the standard, tell about three things you learned?
What are a couple other real-world connections you can make to this standard?

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What Could This Look Like for My Students?

Think about what activities you would want your students to do in your classroom to develop their understanding.

1. Generate 3 lesson activities or ideas that would help students reach mastery of the standard.

2. Use the learning targets from the previous section as a guide of what students need to know.

3. Focus on the standard as an end goal.

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Your Turn

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Describe in at 3-5 sentences each of the 3 lesson activities or ideas you came up with according to the instructions on the previous slide.

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What Resources Could Support Further Implementation?

In this final section, you will use your knowledge of the standard to examine some potential resources. When you look through the resources, it is important to recognize that students need to actively participate in developing their understanding.

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Resources About the Content

Variables with LittleBits

What is here: How variables are used in electronic circuit computing devices that are made for kids.

Resource Link: https://www.youtube.com/watch?v=Jx5Shnsuy74

What is a Variable?

What is here: This is a bit more technical, yet still accessible, definition of variables to extend your knowledge.

Resource Link: https://www.youtube.com/watch?v=Txs3MHINsjI&t=1s

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Resources About the Content

Variables Lesson

What is here: This is actually an animation programmed in Scratch. It might be a fun way to teach your students about variables. You press the spacebar to step through it.

Resource Link: https://scratch.mit.edu/projects/98831292/