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CS Unplugged 4 hour workshops for students

Remember to take good pictures. Examples can be found here:

Ages: 4th grade to adults
Equipment: binary cards, card decks, blue painters tape, colored sticks, pencils with erasers, sidewalk chalk, and pop beads
Additional Resources:

Before each workshop
During each workshop

15 minutes: do pre-surveys (count how many you get and make sure you have all of them)

15 minutes:
Explain that CS Unplugged activities are intended to teach computing concepts without using a computer. Show them the CS Unplugged website and explain that they can look at the activities there as well. Show the dot diva site and either or and explain that they have computing jobs that relate to some of the activities they will do.

30 minutes:
Do the "Error Detection: Card Flip Magic" activity First pick one of the kids to create a 5 by 5 array of cards (5 rows and 5 columns) with some face up and some face down. Then explain that you can add one card to each row and column and then you will leave the room and then one person can turn over one card (and only one) and you will come back and tell them which card was turned over. After you have told them which card was turned over ask them to explain how you knew. You often need to ask them what is different about that row and column to give them a hint. Be sure to explain what this has to do with computer science which is since computers use zeros and ones to represent data and we transmit that data we want to make sure that the data is correctly transmitted. So extra data is added to the message (like adding a card to each row and column) and that data is checked on receipt of the message to make sure the message didn't get changed. Let the kids try this in groups of 5. Have them take turns setting up the array and adding the cards to the rows and columns.

30 minutes:
Do the "Binary Numbers: Count the Dots" activity Use the 5 printed binary cards and put the kids into groups of 5. Have them stand next to each other with 16 on left, then 8, then 4, then 2, then 1 (on the right). Show them how they can make numbers by turning the cards face-up and face-down. Point out that they can make 7 by putting the 4, 2, and 1 cards face-up and the rest face-down. Ask if there is any other way to make 7? Challenge them to make several numbers: 5, 8, 12, and 15. Then have them slowly count up from 0 to 31 with the cards. Ask if they notice any pattern to what happens. Then while one group does this put a "code" on the board with 0 for face-down and 1 for face-up. Then explain that this is the binary number system. And, tell them that computers only use 0 and 1 but that by grouping these "bits" we can make many numbers and even characters. Ask the kids how they think characters are represented using bits? Eventually someone gets the idea that you assign each letter to a number. Ask the kids how high they can count with the fingers on one hand using the binary number system? How about with the fingers on 2 hands? They often guess 64 for the two hands. Walk through the powers of two and show them that with n bits you have 2 to the nth power values (from 0 to 2 to the nth power - 1).

30 minutes:
Do the "Minimal Spanning Tree: Muddy City" activity at Handout page 78 and challenge the students to find the least number of paving stones. When they say they are done ask the number of paving stones and if it is more than 25 ask them to try again. Ask them how they are solving the problem. The "algorithm" for the best path is to start with the shortest and only add a path if it links things that aren't already connected until all are connected. For n nodes it will take n-1 paths. Make the connection to computing networks (as well as gas, water, or electricity).

30 minutes:
Do the "Routing and Deadlock: The Orange Game" activity at Break the students into groups of 4 with one student helper (total of 5 in a group). Arrange the students in a circle and tell each student what color sticks s/he is trying to get. For each group have 2 red, 2 orange, 2 blue, 2 green, and 1 yellow stick. Mix up the sticks and give each person 2 except for the person trying to get the yellow stick. Explain that only the person without 2 sticks can take a stick and they can only take a stick from a person next to them (left or right on the circle). The goal is to get all the people (except the one wanting yellow) their 2 sticks. The one wanting yellow ends up with one stick. If they are having lots of trouble tell them that they may have to give up one of their color sticks during one turn to end up with both. Then move one person in the middle and try again. The person in the middle can take from anyone while the people on the circle can take from left, right, and middle. Which configuration is easier? Which requires more connections? Make the connection to computer networks.

30 minutes:
Do the "Image Representation: Colour by Numbers" activity at Make a copy of page 16 and 17 for each student and have them figure out the pictures. They will need pencils with erasers. Be sure to make the connection to how computers represent pictures (digital cameras).

30 minutes:
Do the flowchart hopscotch. Use the blue painters tape to draw a flowchart on the floor. Make it big enough so that the kids can walk through it. Have them first say their name, then roll the foam dice, and then have a conditional with if roll less than 3 clap your hands and otherwise spin once. Have them say "done" when done. You can also add a loop and have then do the dice roll and action 3 times.

30 minutes:
If you have time you can do either of the following ideas. If it is nice out do the chalk drawing of the sorting network at Otherwise use the pop-beads to have them do a mergesort. Connect the pop beads in random order into one long connected
strand. Then explain that you are going to sort them in ascending order (lowest to highest) with their help. You will break the strand into 2 about equal parts. Then you will give the two parts to two other people. They will each break the strand they receive into 2 parts and give their parts to other people. Each person needs to keep track of who they received the strand from. When it gets down to a strand with only one block in it that one is sorted. So then return that strand to the person who gave it to you. When you receive two strands back from the two people you gave them to they are both in sorted order so merge them back into one strand in order. These keeps happening till it is back to one strand in sorted order. Explain that this is a recursive algorithm.

15 mintues:
Post surveys (count how many you get and make sure you have them all)

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