Let’s Do The Numbers

lets-do-the-numbersWelcome to the number mines of Digitopolis, the famous kingdom from The Phantom Tollbooth! This fall, we hosted a table at Princeton University’s annual Community & Staff Day event. Big crowds meant that we needed something simple, but we wanted to be creative too. Since we had successfully offered the number mines at a massive math event last spring (you can read about it here and here), we decided to bring them back for more numerical fun.

Alas, the original number mine (which was artfully constructed by the Arts Council of Princeton) wasn’t salvaged after the math event. This meant that Katie and I had to build our number mine from scratch. The first part of this post describes how we ran the event table. The second part describes how we build the mine.

At the event, kids would reach into the number mine and pull out a plain wooden number. I bought the numbers online from Woodcrafter, where they range in size, thickness, price, and font. I got the 4″ numbers that were 1/8th of an inch thick. Each number cost 56¢.

wooden-numbersWe found that 4″ was a great size for decorating, but if 56¢ per piece is outside your budget, you can go smaller. A 1″ number of the same thickness, for example, costs 23¢. Or, if you want to go even cheaper, skip the wood and print your numbers on white card stock. We loaded the numbers into the mine, and the kids “dug” them out with their hands.

reaching-in-1Once kids found a number they liked (7 and 8 were very popular), they went over to the number decorating area, which was stocked with metallic makers, glitter markers, small gemstones, and glue. We had a relevant quote from the book on display too. Kids really got into decorating. One little girl spent 25 minutes working on her number!

decorating-the-numbersNote! If you use squeeze glue (as opposed to hot glue) make sure to have paper towels or small paper plates handy so families can safely transport their numbers home. Hand wipes are also a good idea for sticky fingers and tabletops. Katie and I dressed for the occasion in miner’s helmets and safety vests.

dr-dana-and-katie-number-minesSo, that’s our event table…now for constructing the mine! You certainly don’t have to get as elaborate as we did. You can create a mine by covering a box with grey paper. Cut a hole in the box’s lid, throw some numbers in there, and have kids reach into the box! Or you could skip the mine altogether and just do the number decorating part of the project. But if you do want to build a mine, here’s how we did it.


Find a big, flat box that isn’t too deep. You don’t want kids to have to reach too far down for the numbers – especially the little ones. We used a 34″ x 54″ inch box lid, and then attached 6 photo storage boxes to the bottom using hot glue and packing tape. This resulted in a mine that was 5″ deep. Here’s a shot of the underside.

number-mine-step-1Since the box lid didn’t reach all the way to the bottom of the photo storage boxes, we closed the gap by attaching big strips of corrugated cardboard to 3 sides of the mine. We left it the mine open in the back so we could restock numbers during the event.


Cut holes in the top of the box. We found it helpful to draw the holes before we started cutting. That way, we could be sure we weren’t cutting into any of the support boxes and we knew that the numbers would fit through the holes.



Create the rocky, craggy landscape of your mine. We bunched up big pieces of black bulletin board paper and attached them to the box with masking tape.



Now for the really, really messy part. Papier-mâché. We don’t have a sink in our work space, and the nearest bathroom is far, far away. So we wanted to create the smallest mess possible. In other words, we didn’t want to cook, mix, or blend any sort of papier-mâché paste (or dilute any glue). After a little research, we settled on liquid starch.

Below are our tools – 2 enormous jugs of liquid starch, 2 plastic roller trays, and 4 paint brushes (the bristle brushes worked better than the foam ones). Oh, and we also put a plastic tarp under the mine so we wouldn’t ruin the table.

number-mine-toolsSince we had a lot of area to cover, we used big, 6″ x 16.5″ pieces of newspaper. Occasionally, we use a smaller strip for edges or crevices, but mostly we stuck with the big ones.

number-mine-step-4_1The liquid starch held up well! It did coat our hands with sticky residue that required multiple rounds of soap and scrubbing to remove, but it wasn’t too bad. Honestly, the worst thing about the liquid starch was the fact that it was scented. “Mountain Fresh” scent to be exact. Hoo boy. You could smell the mountains the minute you took the cap off. After a couple minutes, the fragrance was looming in the room like a big, ominous fog. Katie put together a little graphic to convey the overpowering Mountain Freshness.

mountain-fresh-freakoutWe left the first layer to dry overnight. For the second layer, we got a little experimental. While researching liquid starch, we learned that some people absolutely rave about using white paper towels and computer printer paper for papier-mâché projects, especially if the projects are going to be painted later. So we decided to give it a try. We papier-mâchéd the bottom of the mine with paper towels, and the top portion with computer printer paper.

number-mine-step-4_2Wow, did the paper towels suck up the liquid starch! The printer paper needed much less. But the printer paper was so stiff, it created unwanted gaps like this one:

stiff-gap-problemThe solution was to drape a liquid starch-soaked paper towel over it. Below is that same gap with the paper towel over it. As you can see, the soft paper towel completely obscures the gap. I didn’t officially test this, but I believe newspaper would obscure gaps as well, perhaps even better than the paper towels.

stiff-gap-problem-solvedI was a little worried the paper towels were too transparent. But overnight, they magically dried to solid white.

number-mine-step-4_3In the above photo, you can see there were still wet patches in crevices where the liquid starch had pooled. Katie hit those with a hair dryer, no problem. And we should add that, even now, things were still smelling quite Mountain Fresh.


Time to paint! We used this awesome textured-stone effects spray paint by Valspar. It’s fun, but pricey ($10 a can at Lowe’s). Our mine required 3 cans.

stone-spray-paintA cheaper option would be to use gray paint to cover the mine, then dab on darker gray  with a piece of sponge. This will get you a textured surface, without the hefty spray paint price. Once the spray paint had dried (which, we might add, finally dissipated the Mountain Fresh fragrance), we decorated some numbers and attached them to the mines with hot glue. We hot glued some large plastic gems on as well – purchased from the wedding favor aisle at Michaels Craft Store.

number-mine-step-5And this, dear readers, is when we discovered the fatal flaws in regards to paper towels:

  1. When dry and spray painted, paper towels become incredibly brittle. I poked a hole right thorough one section while merely tapping on it (we eventually covered the hole with the number 8).
  2. The texture of the paper towel absolutely comes through in the end. So if your paper towels have little hearts embossed on them, you’re going to see little hearts under the paint.
  3. The edges of the paper towels are clearly defined. Unlike the newspaper and the printer paper, you can definitely see the edges of the paper towel under the paint. So our rocky surface looked like, well, draped paper towels. You could even see the dotted perforations that separate the paper towels.

paper-towels-not-goodThe printer paper, on the other hand, was much sturdier and the edges were hidden under the paint. The lesson? DON’T use paper towels for papier-mâché projects. Use newspaper and printer paper instead. In fact, I highly recommend printer paper for the second layer of painted papier-mâché projects. Very sturdy, holds paint very well.

However, paper towels are what we used and their brittle weakness made me and Katie very, very nervous. We were positive that kids were going to put their hands right through the mine as they leaned in to select numbers.

reaching-in-2Anticipating trouble, we brought duct tape and a couple of step stools to the event. The stools elevated the kids right up to table level, allowing them to keep their weight mostly on the stools and not on their hands. So the paper towels held, but there were a couple time you could see them bending. Katie and I would brace ourselves for a tearing, crunching, breaking sound. Thankfully, it never happened. Whew!

Books, Color, Chance

_mur0006The next time you see a telephone book, look beyond the phone numbers, advertisements, thin pages, and wobbly covers. Philadelphia artist Katie Murken did exactly that when she created Continua, a work that combines recycled phone books, color dye, math, elements of chance, and sculpture.

Gathering scores of old and surplus phone books, Katie stripped off their covers and dipped the 3 outer edges into dye. In total, she dyed approximately 1,560,000 sheets of paper with 24 different colors.

dye_readybooks_dryingThen she stacked the altered books into columns. However, the colors she used were determined by a customized color wheel and a pair of dice. A dice roll determined how she would stack the books.

murken_continua_2The result was 24 tall columns of vibrantly colored, gently wavy books pages, arranged completely by chance. And the color! The color! Katie used non-toxic dyes from a small company in California.

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Walking among the stacked pages was incredibly calming, yet energizing. It was also validating. To me, it felt like confirmation of what the knowledge inside books really looks like.

_mur0019If you’d like to see more images of Continua, or read interviews about Katie and her fascinating process, you will find numerous links on Katie Murken’s site.

Photographs courtesy of Katie Murken

Race Around the Clock

race around the clockGo beyond Hickory Dickory Dock with this clever crank clock!  Turn the handle on the back to send the characters dashing around the numbers and through the big red barn (scroll to the bottom of the post to see it in action)!

We read The Clock Struck One, written by Trudy Harris, and illustrated by Carrie Hartman (Millbrook Press, 2009). It’s 1pm and a mouse makes an untimely dash at just the wrong moment, catching the attention of the cat. A chase ensues that involves the mouse, the cat, the dog, some bees, the hen, the farmer’s wife, the farmer’s son, and the farmer! By 11pm, everyone is exhausted. By midnight, everyone is asleep. But at 1am, the clock strikes, and guess who’s in the wrong place at the wrong time again?

Kids loved this clock project, but parents were especially thrilled. Many sought me out after story time to thank me for such a fun introduction to numbers, clocks, and time.

You’ll need:

Begin by stacking both circles on top of one another, and using a box cutter to cut a slit in the middle of both. The top cardboard circle is the clock face. The bottom cardboard circle is the back of the clock.

First, the clock face! Cut, color, and glue (or tape) the numbers from the clock numbers template to the first cardboard circle. You can use markers to add flourishes to the clock face as well (we, for example, added a striped border). Next, trace the barn shape from the clock pieces template onto red poster board. Use markers to add outlines to the barn.

clock barnAttach the barn to the back of the clock face, right above the number 12. I highly recommend attaching the barn with hot glue. You really want the barn to stick because later, it can be used as a carrying handle for your clock! Here’s what the finished clock face looks like:

finished clock faceSet the finished clock face aside for a moment. Cut four, 1.5″ tabs in the end of a toilet paper tube. Then bend the tabs outward and hot glue the toilet paper tube to the back of the second cardboard circle:

clock handleYou’ll notice that the toilet paper handle gets glued on the perimeter of the cardboard circle. We experimented and found that was the best handle position for cranking the clock.

clock handle placementCut and color the animals from the template, and tape (or glue) them onto the ends of the craft sticks. Make sure there’s plenty of room at the bottom of the craft sticks – you’ll need some space to attach the sticks to the clock.

finished clock animalsTape the craft sticks to the cardboard circle. Note – the craft sticks need to be on the same side as the toilet paper tube handle. If the sticks are taped on the opposite side, they will rub and bump into your hand while you’re operating the clock. If you want to follow the order of the characters in the book, the mouse should go first, followed by the cat, dog, bees, and hen.

attached animalsThe back is done, time to put two clock circles together! Push a brass fastener through the clock face’s slit (you might need to enlarge the slit a little with a pair of scissors). Thread 2 foam beads on the fastener’s prongs:

clock tack step 1Push the prongs through the second circle’s slit, then unfold the prongs and secure in place with tape. Depending on your cardboard, foam beads, and brass fastener, you might have to do a little adjusting to get the circles to rotate smoothly.

clock tack step 2

Cut the minute and hour hands from the clock pieces template, then trace them onto red poster board. Arrange the hands to your preferred time, then attach them to the head of the brass fastener with a glob of hot glue. I say “glob of hot glue” because you want the hands to rest on the glob, slightly above the head of the brass fastener. If the hands are pressed flat to the head, they’ll get snagged on the clock numbers later. We stuck green mini dot sticker at the intersection of the clock hands. Done!

finished clockTo operate the clock, grip the clock face firmly at the bottom. Use your other hand to crank the toilet paper tube handle. You might have to adjust the animals a little, or bend the clock hands upward a bit, if they snag on the barn door or the numbers. But eventually, you’ll have a smooth race around the clock!

A quick word about a construction issue. You definitely need a 1.5″ brass fastener and foam spacers to get this project to work. You need that space in between the two cardboard circles in order to grip the clock, turn it, and have it operate smoothly. If the circles are too close together, animals repeatedly knock against your hand while the clock is turning. We experimented with shorter brass tacks, fewer foam beads, handles made out of 8″ craft sticks. Nope. The 1.5″ brass fastener with the 2 foam bead spacers is the combination that worked best!

Want to see my favorite project involving a brass fastener? Check out this little carousel!