# Christmas Computing

Here are some Christmas-linked unplugged computing ideas. There are some extra little Christmas puzzle treats towards the end. Some items are on this site, others are on our CS4FN blog or CS4FN downloads site (which is where you can download all of our free magazines and booklets).

### 1. Do a Christmas Pixel Puzzle Picture

Do one of our Christmas pixel puzzles to learn about how images are represented in a computer and practice numbers while enjoying colouring. Then have the class create their own. Colouring them in relieves Christmas stress too!

### 2. Solve some Elvish Muddlebugs

• The Elves help Santa, but sometimes get in a muddle and make mistakes. Can you spot their mistakes, and help make sure all their work is done and so ultimately all the presents are delivered. Oddly, Elves and programmers make similar kinds of mistakes!
• Improve your logical thinking skills as your sort out the elves problems.

### 3. Write a christmas card writer

Create your own unplugged christmas card writing algorithm and learn about creative programs and some english grammar. (Or write a love letter program or perhaps even combine the two.)

### 4. Christmas Doodle Art

Follow our doodle art algorithms to draw Christmas trees, red berry bushes and snowflakes, while exploring recursion and how it is built in to natural processes and is a way to create computer generated images.

• Create your own doodle art algorithms with a christmas theme. Can you create an algorithm that makes a more realistic Christmas tree?

### 5. Recursive Wrapping

Follow our  recursive wrapping doodle art algorithm to wrap a present using old bits of wrapping paper cut in to squares and joined together to make a patchwork. Will you ever manage to fill the last little gaps?

### 6. Christmas Paper Halving

Surrounded by half torn christmas paper on christmas day? Try this (trivial!) paper folding challenge and learn about divide and conquer. Take the biggest, thinnest piece of paper you can find. Repeatedly fold the paper in half just 10 times.

### 7. Christmas Kriss-Kross Puzzles

• Solve our christmas-linked word puzzle as a way to develop logical thinking and pattern matching skills needed to enjoy both computing and maths, while practicing spelling and counting.
• Have the class create their own Christmas Kriss-Kross (e.g. with nativity-linked words or snowy-day linked words). Having created it they need to make sure it is solvable.

### 8. Solve Santa Syllogisms

• Given some facts about Santa and his elves, what can you conclude using logic alone?

### 9. Christmas Carol Compression Puzzles

• Learn the basics of simple text compression by solving our christmas carol compression puzzles (including one in Spanish). We take a carol and using a simple compression algorithm swap the words for numbers recursively. You must get the carol back before you can sing it.

### 10. Christmas Maths Kriss-Kross Puzzle

• Solve our christmas maths puzzle as a way to develop logical thinking and pattern matching skills needed to enjoy both computing and maths, while practicing doing addition and subtraction. Solve the sums, fit them in to the grid then find some linked sums in the pictures.
• Have the class create their own Christmas Maths Kriss-Kross (e.g. create the sums in a grid, then draw pictures to match them). Having created it they need to make sure it is solvable.

### 11. Hexaflaxagon Christmas Cards

• Create big hexaflexagons and decorate them as christmas cards. Hexaflaxagons are magical, mathematical folded paper puzzles that have hidden sides that appear and disappear as you fold and unfold them. Put christmas pictures on some sides and messages on others. Create a graph-based map of your christmas card to allow you to keep track of what is where. Give it to the recipient in a sealed envelope as the ‘solution’ to the puzzle showing how to find all the messages.

HexaHexaFlexagon stocking filler
Print and make your own hexahexaflexagon and help Father Christmas find the missing gifts.

Options include ready-coloured, black and white for colouring in, blanks to design your own and instructions on how to make from scratch with pencil, paper and ruler if you don’t have a printer

### 12. Christmas Vector Drawing Puzzles

• Follow the instructions to create pictures from shapes and learn about vector graphics. Then create your own drawings. Learn a practical use of the maths of scaling.

### 13. Program an Emotional Elf

• Create emotional elf, snowman or father christmas  robots that you can program to change the emotions on. Use our emotional robot cards as a template to have the class draw their own face pictures with the slots in the same places. Then program the face by pulling the eye, mouth and nose strips to different settings. Perhaps even use them in a puppet show where their expressions change at appropriate points as directed by a script.

### 14. The disappearing snowman or christmas tree magic jigsaw

• Follow our algorithm to make your own magic jigsaw trick for christmas. Give it a christmas theme by making a snowman or christmas tree disappear (we made a robot disappear but it could be anything). You need patience and an eye for detail – as do all computer scientists.
• Or just give our teleporting robot magic jigsaw away as a puzzling present. It will keep everyone out of mischief for a while. Tell them to follow the algorithm and then tell you which robot disappears.

### 15. Decrypt a sinister christmas message from Herod

Play a Victorian Parlour Game out of Dicken’s “A Christmas Carol”

• In “A Christmas Carol” Scrooge’s nephew’s family play parlour games including “Yes/No” which is a variation of 20 Questions so why not play a game, thinking about what makes a perfect question, and why 20 questions should be enough.

### 16. A Magic of Computer Science Magic Show

• Put on a christmas computational thinking magic show (either yourself or get students keen on magic to do the tricks). Pick some simple computer science methods to give after each magic trick, such as what an algorithm is or the fact that misdirection is so powerful shows why interfaces must be so carefully designed.

### 17. Colour-in Christmas and Computing mini booklet ‘zine’

Print out (A4 or US letter size) this one-page colouring-in and puzzle sheet. Once completed follow the instructions on the linked page to fold the piece of paper into a a mini booklet. You can give them away as gifts and the QR code on Santa’s sleigh or the link below it will take people to the linked page too.

### 19. CS4FN Christmas Advent Calendar

In December 2021 we published a blog post every day until Christmas Day, based on the idea of an advent calendar. Each ‘door’ has a picture on it which links to a themed blog post. For example the Christmas jumper post linked to an article on the links between knitting and coding, the patterned bauble linked to a post on printed circuit boards. The post linked to ‘mittens’ was about gestural gloves, digital twins, pair programming and a magic trick (two cards make a pair!). The snowflake took readers to Christmas hexahexaflexagons.

### 20. Computing Jokes and Computing Mottos for your crackers

• Slip computing jokes and mottos in to your crackers this christmas

### Computing Puzzle Treats

Here are some final Christmas puzzles as an extra treat.

I’m not so merry

```I'm not so merry but I'm also sweet
Then look within me for this festive treat
For half my word makes a happy noise
The rest a bad computer employs

What am I ?```

Socks

```Santa has a sack full of those dreaded Christmas presents, socks.
He knows the elves put in 12 pairs of red socks and 4 pairs of green
socks.

How many socks does Santa need to take out of the sack,
in the dark, to be sure he has a matching pair?```

A sleigh full of Rubik’s Cubes

```The elves have made 47 Rubik Cubes. How many must Santa leave at
the North Pole so he can construct a solid cube to put neatly in
his sleigh?```

More ideas to come. Watch this space (of follow @cs4fn on Twitter).

## Answers to the Computing puzzle treats

I’m not so merry …