A Day in Digitopolis, Part I

day in digitopolis part 1We’ve all wanted to jump into books. Who doesn’t, for example, want to go to Diagon Alley and hit the shops? Join Hazel for stories in the Honeycomb? Explore Babilonium with Candy Quackenbush? Or sail the skies with Matt Cruise on the Aurora? Part of my job at the Cotsen Children’s Library is to bring these places to life for kids, and this month, we headed to The Lands Beyond to visit Digitopolis, the mathematical kingdom in The Phantom Tollbooth.

The math event was intended for children ages 4-10, and my goal was to make it full of exploration, demonstrations, games, challenges, and unexpected connections. And by the four million eight hundred and twenty-seven thousand six hundred fifty-nine hairs on my head, I think we did it!

A Day in Digitopolis took place in the atrium of Princeton University’s Frick Chemistry Laboratory, a soaring, three-story structure of glass and metalwork. Here’s our welcome desk with two student volunteers and Pi balloons.

digitopolis welcome deskBut before I get started on all the details, I’d like to introduce our event collaborator, Bedtime Math. Founded by Laura Overdeck, Bedtime Math is a NJ-based nonprofit organization that provides playful, zany math problems for parents to do with their kids everyday. In addition to sharing their content through their books, e-mail, and free app, they created Crazy 8s, an after-school math club that has been launched in over 6,000 locations nationwide. These guys know, and love, math.

bedtime math booksBedtime Math brought 3 fantastic activities to the event: Spy Training, Beach Ball Party, and Glow-in-the-Dark Geometry. Here’s Spy Training, which was all about codes and ciphers…

spy trainingAnd here’s Beach Ball Party, which involved counting, stacking, and chasing beach balls determined to make a break for it.

beach ball partyIt also involved Ellen Williams (who you last spotted being pelted with marshmallows in this post) inflating dozens and dozens of beach balls for kids at the event. That’s her in the lower right corner of the photo, hard at work. Very impressive lungs has our Ellen (did I mention she sings in multiple choirs?).

But the total show stopper was Bedtime Math’s Glow-in-the-Dark Geometry. This took place in a darkened classroom off the main event floor. Here, kids could build illuminated structures with glow stick bracelets and styrofoam balls. The results were totally amazing.

glowing geometrySome kids decided to use the original plastic connectors that came with the bracelets to make unique geometric creations. Here’s one of my favorites. A series of loops that, when spun, becomes a sphere!


Bedtime Math was recently invited to the White House to take part in an early STEM learning summit. Seriously. When it comes to amazing math connections for kids, Bedtime Math has it down!

Moving to a different section of the event floor, we find the fabled number mines of Digitopolis. In the book, Milo, Tock, and the Humbug learn that numbers are, in fact, excavated out of the earth, much like jewels and precious stones. The talented Maria Evans from the Arts Council of Princeton built a 6′ tabletop mine out of cardboard boxes, papier-mâché, Valspar faux stone spray paint, and a couple of giant plastic gemstones I found in our art cabinet. YES!

number mines 1The mines were stocked with an assortment of wooden numbers. I used 4″ numbers I found online at Woodcrafter. If you’d like a cheaper option, I recommend printing paper numbers on card stock.

At the event table, kids reached into the mine, extracted a number, and then decorated it with a combination of metallic markers and glitter markers. We also had plastic gems and glue on hand for some additional bling.

number mines 4number mines 5

number mines 2The mines were staffed by high school volunteers from the Arts Council, who were suitably decked out in miner helmets.

number mines 3Elsewhere in Digitopolis was the “Fibonacci Forest,” hosted by the Stony Brook-Millstone Watershed Association. This table focused on math in nature. Specifically, symmetry, shapes (like spheres, hexagons, spirals), fractals, and Fibonacci numbers. The Watershed brought a ton of items for kids to touch, connect with, and explore (including my personal favorite, this nautilus shell).

nature math 1nature math 2The Watershed also did a cool fractal tree project. It involved a half-sheet of green paper, brown markers, and rulers (here are the instructions if you’d like to see them).

nature math 3We decorated the finished fractal trees with bird and leaf stamps, but you can also just use markers or color pencils.

nature math 4And speaking of wildlife, how about some zebra math? We were delighted to be joined by Princeton University Professor Dan Rubenstein from the Department of Ecology and Evolutionary Biology. Among other things, Dan does field work with African zebras.

zebra math 1Some researchers believe that zebra stripes exist to confuse predators. So Dan and his constituents developed “Dazzle Confusion,” an iPad game in which kids “become the lion” and tried to tap black, white, or striped moving targets to determine which one is most difficult to hit.

zebra math 2At the end of the game, the program tabulated the kids’ results and displayed them on a large screen. As the event progressed, the results continued to accrue. This lead to conversations about data collection, measurement, central tendencies, and averages.

zebra math 3It’s worth noting that although there was much variation on kids’ “strikes” on the targets, there was a strong trend (p < .08) showing that the striped targets were hardest to hit! How’s that for some real world math?

Continuing with the technology theme, the Princeton Women in Computer Science designed an original math game for kids using Scratch, a visual programming language developed by MIT.

scratchHere’s a screen shot of the game, which was created by sophmore Lucy Lin. If you’d like to test drive the game yourself, here’s the link.

scratch screen shotThe game was cool, but even cooler was the fact that there was another laptop running tandem to the gaming laptops that showed all the algorithms behind the Scratch program. And volunteers were on hand to answer any and all questions about computing. They also had a couple of encryption puzzles for kids to crack.

Meanwhile, the Princeton Chemistry Outreach Program (we’ve exploded things with these guys before) was busy making awesome math / science connections with kids. Dr. Wagner and her students ran hands-on experiments with parts per million, vitamin c clocks, and timed invisible ink.

chemistry outreach 1chemistry outreach 2chemistry outreach 3For those who prefer their math undiluted, the Princeton University Mathematics Club came out en force to host a “Playful Problems” table. Here, kids found a plethora of logic puzzles, word problems, visual puzzles, calculator tricks, the works!

math club 1math club 2There were 12 different activities for children ages 4-10. The activities ranged from easy to moderately difficult. Here’s an example of our simplest puzzle, which was created by Casandra Monroe (whom you first met here). Here’s the template if you’d like it.

milo number grid puzzleBelow is a list of what we offered at the event table (if you’d like more details on any of them, just e-mail me!). In addition to using Google to find some of these puzzles, Math Wizardry for Kids (Barron’s, 1995) and How to be a Math Genius (DK Children, 2012) were terrific resources.

  • Suduko
  • Lattice multiplication
  • Logic grid puzzle
  • Matchstick puzzles (we used Q-tips instead of matchsticks)
  • Milo number grid maze (see above)
  • 24 Game
  • Multiplying by 9 finger trick
  • Make a paper star with only 1 cut
  • Superimposed shapes puzzle
  • Visual sequencing puzzle
  • Word problems
  • Birthday calculator trick

Important! If you put together your own Playful Problems table, make sure you provide an answer sheet for each problem. That way, parents and kids can check their answers or get a little hint. Also important! No matter how easy the puzzle, provide an answer sheet (you don’t want younger kids to think that their puzzle was too “easy” for a solution sheet).

For those wanting a bit a exercise with their mathematics, we had a giant 16′ x 16′ floor maze (building instruction for it are in this post). Kids had to get from start to finish in the maze – without making a single right-hand turn. If you got stuck, the solution was posted on some glass doors opposite the entry to the maze.

no right turn maze at eventBy the way, did you notice the cute play cart parked in the upper right corner of the above image? That’s one of our “Trio of Treats.”

trio of treatsI always try to include something for the littlest patrons, so I bought 3 adorable food carts and stocked them with math play sets. The food carts are by KidKraft (Sweet & Sunny Lemonade Stand) and the play sets are by Learning Resources. We used  Piece-A-Pizza Fractions, Number Pops, and Count ‘Em Up Popcorn.

And, because little kids love to take things in and out of containers, I bought a fabric basket for the pizza cart, a plastic box with a hinged lid for the ice pop cart, and a clear container for the popcorn cart. After the event, we donated the carts and math sets to a local non-profit preschool.

trio of treats customerOne of the most popular event tables, however, was “Visit the 4th Dimension.” It was hosted by scienceSeeds (whom you first met here, and then again here).

scienceseeds 1At the event table, kids learned about the different dimensions (1st is a line, 2nd is a square, 3rd is a cube, 4th is a tesseract). ScienceSeeds brought their 3D printers to the event and made models. You can see a tesseract in progress below. Awesome.

scienceseeds 2Kids could also make 3D models of their own using drinking straws and plastic connectors. You can buy the plastic connectors online (from Strawbees). However, scienceSeeds has a die cut machine and was able to purchase the die cuts (from Accucut) and make their own connectors from plastic sheets (from Grafix).

scienceseeds 4Like I said, their table was hopping – they estimate they went through at least 3,500 straws!

scienceseeds 3The thing I liked most about the project is that there was no limit to the shape, size, or intended use of the 3D models.

3D model 13D model 23D model 53D model 33D model 4

If plastic connectors are not in your budget, I’ve seen similar activities that used straws and pipe cleaner pieces (like this one), or sculptures that that involved cutting and sliding the ends of bendy straws into one another (like this one). I’ve also seen toothpick and marshmallow, (or toothpick and gum drop) geometric structures. But I tend to avoid those because of food allergies.

Whew! Believe it or not, I’m only halfway through all the event activities! You can check out Part II here…prepare to meet Digitopolis’ famous celebrities, get a bit of hands-on history, listen to some musical fractions, and view some truly stunning representations of infinity…

Incredible Illusions

incredible illusionsBehold the mystery…the wonder…the spectacle…of your very own mini magic show!

magic tricksThis project was the culminating event at To Be Continued, our weekly story time for 6 to 8-year-olds. Every week, we read from a chapter book and celebrate the the end of the entire book with a project and/or activity.

We read Horten’s Incredible Illusions by Lissa Evans (the sequel to Horten’s Mechanical Mechanisms (Sterling Children’s Books, 2012)). Young Stuart Horten moves to the town of Beeton and expects to be thoroughly bored. However, he soon discovers that he is part of a magical legacy left by his Great Uncle Tony, who was a stage magician and illusionist. In the first book, Stuart and his friend April solve a series of complicated clues and find Uncle Tony’s secret workshop. In the sequel, the friends again embark on a journey. This time, they’re searching for Great Uncle Tony’s will, which bequeths the contents of his workshop to whoever finds the document first. Clues are hidden in each of his magical stage illusions, but…the magical worlds inside the illusions are real and in some cases, dangerous. And Stuart and April aren’t the only one interested in getting their hands on those tricks.

We definitely needed some incredible illusions to celebrate the conclusion of these awesome books. I designed these individual mini magic shows to be easy enough for 6-year-olds to do, but intriguing enough for 8-year-olds. After consulting a number of children’s magic books, I found Amazing Magic Tricks: Beginner Level by Norm Barnhart (Edge Books, 2008) to be the most useful. The 4 tricks described in this post are from this book.

You’ll need:

  • 1 memory box (more about this below)
  • A 10.5″ piece of PVC pipe (05.” in diameter)
  • A selection of colored masking tape
  • 1 paper cup
  • 1 paper (or fabric) flower
  • 1 empty seed packet (or small envelope simply marked “Magic Seeds”)
  • A 9″ x 12″ piece of felt (I used the glitter variety)
  • hat rabbit carrot template printed on 8.5″ x 11″ card stock
  • 1 Styrofoam coffee cup
  • A selection of foil star stickers
  • 2 playing cards
  • A 1″ foam paintbrush (or regular paintbrush)
  • Scissors and tape for construction

You’ll need a box with a lid to store your tricks and shield your hands from the audience as you prepare your tricks. A memory box is perfect for this. I purchased mine at Michaels Craft store. I went with black, but they come in all sorts of colors and patterns.

memory boxDecorate the lid of your box however you like (I found some self-adhesive glitter foam stars in the clearance section at the craft store) then slide the lid onto the box like so. This creates a “screen” and a “backstage” area to prep your tricks.

magic boxNext, wrap colored masking tape around the PVC pipe. Your magic wand is ready!


The most important thing about this trick is making sure the flower is small enough to hide in your fist. I purchased 1.25″ paper flowers for the kids (scored on discount from the scrap booking section of the craft store).

flowerBehind your box’s screen, grab the flower in your fist. Then use the same hand to hold the paper cup with your fingers.

flower trick 1To perform the trick, show the audience that your cup is empty. Then say “Oh no! It’s empty. Well, good thing I have some stupendous magic seeds!” Pick up the empty seed packet and pretend to pour seeds into the cup.

flower trick 2Wave the wand around muttering magical incantations. While the audience is distracted by the wand, open your fingers and drop the flower into the cup. Shout “Ta da!” and show them that a flower has magically appeared!

flower trick 3TRICK #2: FIND THE RABBIT

Print the hat, rabbit, carrot template. Fold and tear the strip in 2 places, like your see below. It’s really important that your TEAR the strip. Don’t cut it with scissors!

rabbit trickTo perform the trick, hold up the 3 image cards and say “You see a hat, a rabbit, and some carrots, but with my amazing magical skills, I will pull the rabbit from under this cloth every time!” Turn your back and have an audience member arrange the 3 image cards on the table and cover them with felt.

rabbit trick 2Reach underneath the felt and feel the edges of the image cards with your fingers.

rabbit trick 3The rabbit will be the only image card with two torn edges. Remove it from under the cloth with a flourish! Repeat with a difference audience member. Astounding!

rabbit trick 4TRICK #3: BALANCING CUP

First, decorate a Styrofoam cup with foil star stickers. Next, cut a playing card in half, lengthwise. Tape one half of the cut playing card to the back of another card. The half of the playing card should “hinge” outward like so

cup trick 1To perform the trick, flatten the hinge to the card and hold it up to your audience, keeping the taped side facing your body. Invite an audience member to come forward and try to balance the Styrofoam cup on top of the card. Then say “You see it is impossible. But I will now use magic to make the impossible, possible!”

While you’re talking, sneak a finger up the card and open the hinge on the back, forming an area for the cup to balance. From the side, it looks like this:

cup trick 2But from the front, it looks like the cup is now balancing on the card!

cup trick 3TRICK #4: MAGIC GLUE

To perform this trick, tell the audience that you have magic glue. Hold up a paintbrush and Invite an audience member to come up and “paint” your hand with the magical glue. For my version of the trick, we used 1″ foam paintbrushes I had left over from another program.

wand trick 1Now hold the wand in your “glued” hand. Say “Observe my stupendous magical glue!” Extend your arm across your body and out to your side, still grasping the wand. Next, wrap your free hand around the wrist of your wand hand. Slowly and dramatically, lift each finger from the wand until you no longer appear to be holding it.

wand trick 2But you are holding it of course. Because when you grasp your wrist, you sneak a finger behind your wand hand and hold the wand like this:

wand trick 3Now have the audience clap once to have the wand “detach” from the magic glue. Carefully lift your finger to release the wand, and let it fall dramatically to the floor. Take a big bow.

The kids absolutely loved this project. I performed the whole show first, and then I deconstructed all the tricks and each kid made his/her own set. If, by the way, you’d like to see the awesome mechanisms we made after reading Horten’s Miraculous Mechanisms (the first book in this set), click here.

In May 2015, I interviewed Lissa Evans about her fantastic books. If you’d like to hear it, click here!