Placeholder Image

字幕列表 影片播放

  • 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:

  • Cost of red beads x number of red beads Cost of blue beads x number of blue beads

  • Cost of thread x length of thread

  • 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

  • pump in Broad Street...”

  • 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

  • to check your understanding.

Pattern Recognition

字幕與單字

單字即點即查 點擊單字可以查詢單字解釋

B1 中級

計算思維。模式識別 (Computational Thinking: Pattern Recognition)

  • 65 11
    Chris Lyu 發佈於 2021 年 01 月 14 日
影片單字