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• Pattern Recognition

• Have you ever noticed patterns in nature? Such as the different time the sun rises each

• day, or the schedule of the ocean tides?

• How about patterns in your school work? Poems, such as limericks have a pattern that sets

• them apart as a type of poem. Shakespeare’s plays contain patterns--they are written in

• unrhymed iambic pentameter which is a pattern of ten stressed and unstressed syllables.

• Patterns can be identified in art, as well, such as Van Gogh’s distinctive brush strokes.

• In the process of observing and breaking down a problem into easier to solve smaller pieces,

• you will likely have noticed similarities and patterns. You may have identified patterns

• within the subproblems or among them.

• For example, returning to the necklace problem, you may have noticed similarities between

• each of the smaller subproblems identified:

• What is the cost of the red beads? What is the cost of the blue beads?

• What is the cost of the thread?

• The operation to find each answer is the same:

• Each subproblem calculates the cost of the material by determining how much of each material

• was used. This pattern of similar subproblems aids us in determining how to find the answer

• to the larger problem. Stay tuned as we will continue with this problem in the next video.

• Patterns are opportunities for efficiency when solving problems.

• Being able to recognize patterns is a fundamental step in the process of problem solving with

• computational thinking because the patterns help you determine what operations can and

• need to be done. This is critical in moving forward in computational thinking, especially

• if the goal is utilizing computers to automate and streamline a process. If the same operation

• occurs again and again, it may be able to be entered once and repeated.

• Let’s explore some classic examples of patterns in problem solving.

• Codes are systems of symbols used to represent other symbols to disguise messages. To be

• able to decode this type of message, the user must identify the pattern used for symbol

• substitution.

• For example, a very simple code might be based on a pattern of numbers representing letters,

• such as 1=A, 2=B, 3=C, etc.

• To make a code like this more difficult to break, the letter number patterns may be shifted—1=M,

• 2=N, 3=0, etc.

• When trying to decipher a code, the decoder has to recognize the pattern being used for

• the code in order to break itunless they are lucky enough to have a decoder ring. Decoder

• rings are mechanisms that efficiently use the code pattern to unlock a code based on

• symbol substitution.

• The most famousdecoder ringin history is the Rosetta Stone. The Rosetta Stone is

• an actual stone that was discovered inRosetta” (el-Rashid) Egypt in 1799. Prior to its discovery,

• the hieroglyphs of ancient Egypt remained a mystery, as knowledge about what they meant

• had been lost over time. The importance of the Rosetta Stone is that the same passage

• was carved into the stone in three different languages. Codebreakers were eventually able

• to use a language they knew to learn what the symbols they didn’t understand meant,

• thus unlocking the secret to reading hieroglyphs and learning about ancient Egypt.

• Cholera in London Another example where pattern recognition

• played a role in problem solving occurred in London in the late 1800’s. Many of London’s

• residents were ill with cholera (an infection of the small intestine that can lead to vomiting,

• diarrhea, dehydration and eventually death), but disease spread was poorly understood at

• the time, so it was unclear what the source of the outbreak could be. Through investigation

• and deduction, a London doctor named John Snow hypothesized that Cholera was spread

• through contaminated water and identified patterns as to when and where illness was

• occurring in relation to water sources to locate the cause of the outbreak, one certain

• contaminated city water pump.

• In John Snow’s own words: “On proceeding to the spot, I found that

• nearly all the deaths had taken place within a short distance of the [Broad Street] pump.

• There were only ten deaths in houses situated decidedly nearer to another street-pump. In

• five of these cases the families of the deceased persons informed me that they always sent

• to the pump in Broad Street, as they preferred the water to that of the pumps which were

• nearer. In three other cases, the deceased were children who went to school near the

• Due to John Snow’s pattern recognition and problem solving skills, the pump was disengaged,

• the cholera epidemic was stopped, lives were saved and our understanding of waterborne

• diseases grew.

• A third example of pattern recognition used for problem solving is more recent. Around

• 2007, an art collector purchased this chalk on vellum (animal skin) drawing of a young

• girl. He boldly suspected that the artwork could be attributed to Leonardo Da Vinci,

• painter of the Mona Lisa and The Last Supper. Experts from the art world got involved and

• started looking for patterns--features of the piece that were consistent with known

• Da Vinci style, as well as other scientific and historic clues that might mean it was

• a Da Vinci work. Through their investigation they found a long list of evidence (enough

• to publish a book on the topic) that the drawing was in fact created by Da Vinci. The patterns

• identified include: • exquisite details, such as the way the

• girls headband curves her hair and her fine eyelashes

• the age of the vellum, determined through carbon 14 dating, on which the girl is painted

• is consistent with when Da Vinci livedpen and ink lines discovered under the

• chalk layer using super high resolution photography that indicated a left handed artist (which

• Da Vinci was) as well as similar drawing habits to Da Vinci’s other works

• • A fingerprint preserved in the chalk--which unfortunately turned out to be inconclusive

• attempting to recreate a copy of the artwork in the same style determined that the materials

• and style were very unique, used experimental binders to make the chalk stick, and would

• have been challenging to work with--Da Vinci similarly experimented with binders when working

• on The Last SupperThe girl in the drawing’s hairstyle

• was identified to be from Da Vinci’s time and more specifically attributed to a specific

• royal family for whom Da Vinci served as an artist. The girl was identified to be the

• daughter of Da Vinci’s employer. • Finally, the jagged left edge of the vellum

• and three small holes led to experts to believe the drawing came from a page in a book. The

• book was traced to the National Library in Poland where it was found to match exactly.

• Since Computational Thinking can be used in any subject area, the type of patterns to

• be recognized vary widely. Let’s look at how pattern recognition can be used to address

• some different types of problems.

• The Computational Thinking activity provided by studio.code.org is an excellent offline

• activity that demonstrates the Computational Thinking process visually as studentsmake

• a monster”. The decomposition and pattern recognition steps are closely related in this

• case, so both are introduced here. This activity will be used again in the last two videos.

• The goal of the activity is for students to design an efficient method (program) for others

• to be able to recreate drawings of monsters with unique sets of features. These are the

• monsters.

• The first step is decomposition and pattern finding. What features do these monsters have

• in common? How can we group features? Ask students to list/group features.

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

• They all have eyesThey all have a nose

• They all have a mouthTwo have ears, one does not

• Next, have students use tracing paper to physically group features. They can name the features

• based on the monster’s name. We will continue with this activity in the next video.

• There are many, many great online resources for practicing recognizing patterns. Visit

• the suggested activities for this section to find links to a variety from different

• subject areas. Several are described here.

• The Pattern Generator at shodor.org generates an ongoing variety of different types of patterns.

• If you want to focus on numbers and math related-patterns, try The Empty Triangle and Number Cracker.

• For English/Language arts-related patterns try Syntax Store, which focuses on sentence

• structure and Limerick Factory which plays with poetry.

• People Patterns combines visual pattern recognition with math in levels of increasing difficulty.

• Guess my Button is another visual pattern recognition game.

• Another great way to practice recognizing patterns is through drawing. Students can

• search for instructions and methods for drawing just about anything they would like. For example,

• a quick search resulted in a method for sketching a horse that begins with abstract shapes and

• steps through a process toward a detailed and recognizable horse. A similar method is

• used when drawing a portrait.

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