Center for Embedded Networked Sensing University of California, Los Angeles CS4HS Workshop July 23, 2009 And kinesthetic computer science activities Lynn Lambert Christopher Newport University Newport News, Virginia

Author: Tim Bell (not pictured: Ian Witten and Mike Fellows)

Global project New Zealand Sweden United Kingdom Korea Japan China Haiti Even USA (CSTA, Peter Denning, Carnegie- Mellon, SIGCSE, AP Reading, NECC)

What is Unplugged How to teach important computer topics without using computers at all!computer topics Have Fun!

Like? Binary Numbers Image Representation Text Compression Error Detection and Correction Searching Algorithms Sorting Algorithms Sorting Networks Minimal Spanning Trees Routing and Deadlock Finite-state Automata Programming Languages Information Theory

Magic Trick Make a 5x5 grid with colored squares, some with one color, some the other. Magic

Even parity Can detect a bit that was corrupt ISBN detects adjacent swapped digits or a single incorrect digit X 10 = (1x 1 + 2x 2 + 3x 3 + 4x 4 + 5x 5 + 6x 6 + 7x 7 + 8x 8 + 9x 9 ) mod 11 Harry Potter and The Deathly Hallows: (0*1 + 5*2 + 4*3 + 5*4 + 0*5 + 1*6 + 0*7 + 2*8 + 2*9 ) ( ) = mod 11 = 5 Parity Checking

Binary Digits

BINARY NUMBERS HAPPY BIRTHDAY, Daniel Radcliffe ! Born July 23, 1989 Daniel Radcliffe turns

Characters in Binary H E L L O 1234 ABCD 5 E E 6789 FGHI 10 E J L M N 15 E O P Q RS 20 E T UVWX 25 E Y K 26 E Z

Characters and Sound Represented in Binary “ASCII” Modem

Each pixel is a bit Image Representation (black and white) 1440 * 900 = 1,296,000 pixels/bits

Each pixel is a bit for first row etc. Image Representation (black and white)

Image Compression Run Length Encoding 4, 11, 2 4, 9, 2, 1, 1 4, 11, 2 4, 9, 4 5, 7, 5 0, 17 1, 15, 1

Each pixel is a bit Still 1,296,000 pixels Now, each pixel is Image Representation (Color) 32 bits

Color Images RGB color for blue Microsoft Office Color

204/102/0 226/113/0 196/198/0 226/113/0180/90/0 141/105/ /240/255230/206/ /102/38 141/105/ /238/228218/218/200217/187/63

Routing and Deadlock Orange Game

TREASURE HUNT: Finite State Automata (FSA) FSA are theoretical state models Unplugged uses a treasure hunt. Others: letters to accept particular words a metro map for getting to a particular location

TREASURE HUNT What is the quickest route? Finite State Automata

“Yesterday” by The Beatles L-Z Compression Yesterday love was such an easy game to play Now I need a place to hide away Oh, I believe in yesterday. Why she had to go I don’t know, she wouldn’t say. I said something wrong Now I long for yesterday.

MARCHING ORDERS Programming Languages One of the most frustrating things about programming is that computers always obey the instructions to the letter, even if they produce a crazy result.

CS Unplugged in High School (by Scott Fletcher) Perfect: Binary Numbers, Programming Languages ("first day exercise“). Image Representation to introduce computer graphics to the students. Text Compression (used a popular song that the kids would recognize) Used briefly to introduce a topic: Twenty Guesses or the Card Flip Trick Sorting Networks Algorithm, Minimal Spanning Trees, Treasure Hunt could have been more challenging Did not use: Battleships (pretty involved) Lightest and Heaviest (too much equipment) Orange Game (but should have)

Have you used Unplugged? How?

Sorting and Searching In the book Battleship (Searching) Lightest and Heaviest (Sorting) Sorting Network Your ideas

FIND SHIP # 9264 BATTLESHIPS: Search Method 1 GAME 1: Ships are in random order.

BATTLESHIPS GAME 2: Ships are in increasing order. FIND SHIP #

BATTLESHIPS GAME 3: Ships are ordered into 10 groups based on the sum of the digits of the ship modulo 10. FIND SHIP #

BATTLESHIPS These three games illustrate linear search binary search hashing What is the maximum number of guesses required for each of these search techniques for n battleships?

LIGHTEST & HEAVIEST Start with a few (6 or 8) containers with different amounts of sand or water inside. Seal tightly. Children are only allowed to use the scales to compare the relative weights of two containers. Only two containers can be compared at a time.

LIGHTEST & HEAVIEST: Method 1: Selection Sort Find the lightest of the containers using the weights they have been given, using only the balance scales. Now compare that with another, keeping the lighter from the comparison. Repeat until all the objects have been used.

LIGHTEST & HEAVIEST METHOD 2: Quick Sort Choose one of the objects at random. Compare each of the remaining objects with it, and put them in one of two groups. Put those that are lighter on the left of the object in the middle, and those that are heavier on the right (there may be no objects in one of the groups). Repeat this procedure on each of the groups— that is, use the balance to divide the groups into subgroups. Keep repeating on the remaining groups until no group has more than one object in it. The objects will be in ascending order.

Sorting network < > Right Left

Sorting and Searching In the book Battleship (Searching) Lightest and Heaviest (Sorting) Sorting Network Your ideas

Non CSUnplugged Activities Andy Begel, Steve Wolfman, Dan Garcia KLA (Kinesthetic Learning Activities), Binary Tree Recursion cons, car, cdr AP Reading Toy Night with Robert Duvall Internet, Sorting, Searching AP list, CSTA

THE MUDDY CITY Our society is linked by many networks: telephone, utilities, roads For a particular network, there is usually some choice about where the links can be placed. This exercise examines a complete network to determine the links necessary to connect all the components of the network at minimal cost.

THE MUDDY CITY

a graph

THE MUDDY CITY a graph

THE MUDDY CITY This exercise illustrates how to build what we call the “minimal spanning tree”. A tree does not have any cycles where you can get back to where you were before. This exercise does not give us the shortest path from one location to another. But there is another algorithm for that!

Peruvian coin toss Try for a fair coin toss over the phone

Information Theory Can you read the following sentence? Ths sntnce hs th vwls mssng. You probably can, because there is not much "information" in the vowels. This activity introduces a way of measuring information content.

Shannon theory Twenty questions Guess a number

Shannon theory Guess a letter Guess a sentence Probability and information

Your Turn Break up into groups, and answer at least one of the following: 1.What unplugged or unplugged-like activities have you done in your classroom? What worked/didn’t work? 2.Create an activity that you and others can use in a classroom.

Example mappings 1.What unplugged or unplugged-like activities have you done in your classroom? What worked/didn’t work? 2.Create an activity that you and others can use in a classroom. Props you can use Cards two sides, choice, combinations, permutations Cups, containers, buckets hidden information, two states, variable, limited contents Stickers, marker pen commit, label, colour, user input Chalk on pavement/ tape on floor transitions, paths, target Board game paths, chance, rules Food competition, humour, colour, sharing, size String Connection, communication, length, network

Your Turn Reporting

Cryptography Public/Private Key One Way Functions Send Information

One way function Both have the same telephone book Pick a function Odd/even length of name Name begins with H/T

Select name

Record phone number

Presenter guesses: H or T?

Presenter tries to find name

Human-Computer Interaction ≠

Stop the computer...

HCI Works sheets Affordances for doors Layout of ovens Dumb interfaces System is machine plus user

CS Unplugged wants your ideas: Designing an activity What are the key elements? e.g. bits, states, compare, relationships What games/puzzles/toys use similar elements? Turn it into a challenge To find (best) solution Compare speed (of groups or methods) Team? Impediments? Evaluate Simplicity, engagement, cost, novelty Refine Show to lots of kids/teachers/profs Publish

Questions?