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• Abstraction and Pattern Generalization

• Abstraction in Computational Thinking allows for the creation of a more generalized model

• of the complex problem being solved. Abstractionlets one object stand for manyand

• allows us to deal with complexity and scale. Using what you learned by recognizing patterns,

• relevant variables can be identified, grouped and generalized (described with less detail)

• so that they define the main ideas of a problem.

• The key to abstraction is to be able to identify and filter out or ignore the details not necessary

• to solve the problem. From there, a model (equation, image, word, simulation, etc.)

• can be developed to represent all the important variables. A variable is a name that can be

• associated with a value. Variables have changing values and can be represented by a number,

• letter, word, blank or image. Often, the value of one variable will determine, or be dependent

• upon, another. In these examples, you can see how the value of the second variable,

• or input, is dependent on the value of the first variable or input. Abstraction allows

• you to create a generic representation of a problem.

• Pattern generalizationis creating models, rules, principles, or theories of observed

• patterns to test predicted outcomesIn other words, Pattern generalization is figuring

• out the right relationship between the abstracted variables to accurately represent the problem.

• Recognizing patterns as we did in the last video is critical, as patterns are almost

• always where generalizations begin. What an abstraction looks like depends on

• the type of problem being solved. Here are some abstractions across different areas and

• problem types:

• Science Examples of abstractions in science include

• simplified models of the water cycle, nitrogen cycle, rock cycle, etc. Classification of

• living things can also be considered abstraction--we use words like mammal to generalize groups

• of animals, or marine organisms to generalize life in the ocean. In Chemistry the periodic

• table is an abstract diagram representing lots of information about much of human knowledge

• relating to earth’s materials.

• Math Most of mathematics involves abstraction.

• Even something as simple as a triangle is an abstraction of points, lines and angles.

• Art In his painting Three Musicians Pablo Picasso’s

• abstract shapes and colors come together to form a picture that we recognize as three

• individuals playing instruments.

• English When we learn a language, we learn about how

• different parts of speech come together to form a sentence. Here is an abstraction of

• a basic sentence structure in English.

• Subject (person or thing) + action/occurrence/state of being + object (person or thing)

• OR

• Noun + verb + noun

• For example: Susie ate pie.

• The dog ran home.

• a blank is given where any noun, verb or adjective can be placed. The result is grammatically

• correct sentences with some pretty silly meanings!

• Universal symbols Every day we encounter familiar symbols that

• are so commonplace in our lives we rarely notice them. However, these abstractions truly

• dolet one object stand for many”. See if you know what message each of these symbols

• represents.

• Let’s start by using abstraction with a familiar problem. We previously decomposed

• the problem into three smaller subproblems to be added together and identified the patterns

• between how those subproblems can be solved. The subproblems are:

• We can now use abstraction to simplify the problem even further into one repeatable operation:

• Material cost x material quantity The variables are

• 1. The cost for each type of material 2. The quantity of each material

• Through abstraction we have created one operation that can be used to determine the cost of

• each of the three materials. In the final video we will return to this problem and discuss

• an algorithm for solving the entire problem. Abstraction helps us to create models related

• to a problem that can work for large quantities and ranges of data. Suppose you wanted to

• calculate how much it would cost to make a 10 foot garland out of red beads and thread,

• or calculate the cost to create 250 necklaces, or calculate how many 24 inch necklaces using

• an alternating pattern of 3 red beads and 3 blue beads could be made for a certain budget?

• can make it easy to model or calculate different options.

• Other examples of abstraction being used to create models that allow testing of different

• variables and situations include:

• Learning about gravity and acceleration using a physical model (a ramp and ball) at a very

• young age, in a lab as a middle school or high school student using graphing to model

• changing variables, or as an engineer. Let’s continue with another example from

• the last video, the Make a Monster example. In the last section we listed patterns or

• similarities that the different monsters had in common. Here is what we found:

• What do all the monsters have in common? • The all have a head

• They all have eyesThey all have a nose

• They all have a mouthTwo have ears

• We know from looking at the pictures that there are several options for different head

• shapes, eyes, noses, mouths and ears (including no ears). Using abstraction, we now want to

• modify these statements so they could describe the qualities of any monster. For example,

• This monster has a blank head. This monster has blank eyes.

• This monster has a blank nose. This monster has blank ears.

• This monster has a blank mouth.

• In this case, the variables are as follows:

• Heads: Zombus, Franken and Happy And eyes, ears, noses and mouth: Vegitas,

• Wackus and Spritem

• If a monster doesn’t have one of these features, we can call that InHideum.

• In the last video we will learn how to take this abstraction and use it to give instructions

• to another person to recreate any monster! Here are some other examples that you can

• use in your classroom to practice abstraction: A Dichotomous Key provides a process for identifying

• something based on its features. This can be an animal, plant or candy--the process

• is the same! Like in Make a Monster, in this activity the student is responsible for abstracting

• the characteristics of several different types or varieties of something--in this case candy.

• By organizing those abstractions into a dichotomous key, they create a tool that can be used by

• others for identification purposes. As mentioned earlier, Mad Libs are created

• through abstraction of a sentence. Mad Libs can be done on paper, such as in the activity

• Mad Glibs from studio.code.org, or they can be generated online.

• In this activity students first go from specific to general, by carefully describing an everyday

• object using general terms so that someone who didn’t know what it was could understand.

• Students then trade descriptions and try to figure out what each other was describing.

• Working with tangrams involves abstracting geometric patterns--using shapes to create

• other recognizable shapes. This becomes a game at GeoShapes on National Geographic Kids.

• Challenge your studentswho can solve the tangrams problems the fastest?

• When you have finished watching this video, don’t forget to complete the quick self-evaluation

Abstraction and Pattern Generalization

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# Computational Thinking: Abstraction and Pattern Generalization

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Chris Lyu posted on 2016/06/04
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