Experiment: Cold Water Currents

My son checked out the book Awesome Ocean Science by Cindy Littlefield,* and decided to try the experiment on Deep-Water Currents (pg 32).  In this experiment, you fill a baking dish with tap water, put an ice pack in one end, drop one drop of food coloring in the water near the ice pack, and drop another drop near the opposite end of the pan.  The food coloring near the ice pack starts moving in a streak towards the far end, while the opposite drop does not spread, showing how cold water from the ice pack pushes warmer water away.

Dye dropped in water near the ice has been pushed to the side, forming the streak.  
Dye dropped in the corner away from the ice has formed a stationary puddle.

Since I hate using food coloring near small children (think of the stains!) and since I'm always wondering what candy will do in any situation, we decided to try this as a candy experiment.  We set up our pan again, dropping single M&Ms in the water near the ice.  Would the cold water push the candy dye?

M&Ms dropped in water near ice pack.  The cold water has pushed the dye away in a streak.

As you can see, the first part of the experiment worked very well.  The moving cold water pushed the M&M dye away from the ice, forming lovely streaks of color.  Next we tried the experiment as instructed by the book, with M&Ms placed both close to the ice and far away.  We expected the furthest M&M to dissolve into a round pool of color, as had our dye drop.  But it didn't work quite that way.

M&Ms placed in water with ice pack. The color from the M&Ms in the corners has spread towards the ice pack, while the color from the M&Ms near the ice pack has spread away from the ice.
The M&M color in the corners didn't stay put.  Instead, it pushed back towards the ice packs.  Were we doing the experiment wrong, or was there another explanation?

I think there was another force acting upon the M&M color.  As candy dissolves, the denser sugar water sinks to the bottom.  With water continuing to sink, the widening puddle of color is pushed away from the candy.  Since we'd placed our candy in a corner, the color had no place to go except towards the ice pack.

*Littlefield, Cindy A. Awesome Ocean Science.  Nashville, TN: Williamson Books, 2003.

Cacao: Chocolate in Infancy

My recent trip to Costa Rica showed me wonders I never thought I'd see in real life: wild parrots, foraging monkeys, and a river full of crocodiles.  But the most exciting sight to a candy experimenter's eyes?  A real life cacao tree.

Cacao flowers grow on the branches and trunk of the cacao tree throughout the year.* We spotted two tiny flowers sprouting from the main trunk well above our heads.

The flowers become pods, which take 5-6 months to grow to full size and mature.* We could only see one empty pod on our tree, chewed through by a foraging animal.

The beans from this cacao tree are far removed from the chocolate in my gourmet bar.  After harvest, cacao beans must be fermented, dried, cleaned, roasted, and ground before they start to approach what I know as chocolate.*  Furthermore, since this tree was located in Costa Rica's Las Pumas Rescue Center, its beans will never turn up in my chocolate blooming experiments.  Still, as I admired the tree, I felt as if I were greeting an old friend.

*See Stephen T Beckett, The Science of Chocolate, page 14
*See Stephen T Beckett, The Science of Chocolate, chapters 2-3

Highlights Magazine gives award to "Candy Secrets" article

I was very pleased to have my article "Candy Secrets," about candy experiments, published in Highlights magazine last October.  Apparently the editors were also pleased by the article, because I have just received their Pewter Plate Award for "Nonfiction Feature of the Year."  It's an actual engraved pewter plate, delivered to my doorstep yesterday afternoon.

I knew candy experiments were changing the world, but I didn't realize they'd been so well received in the world of children's literature.  Thanks, Highlights!

A Healthy Airplane Snack?

On a recent family plane trip, my husband bought a snack to keep my toddler happy for a few minutes.  He chose the $3 Cranberry Nut Mix, which contained "Raisins, Cranberries, Yogurt Raisins, Yogurt Cranberries, Almonds & Walnuts."  A healthy choice?

Not as healthy as he thought.  "Yogurt" confectioner's coating, according to the USDA, is 62% sugar and 27% fat.  (Ours also contained the artificial color titanium dioxide--that bright white doesn't come from yogurt!)  Sweetened cranberries are 65% sugar according to the same website.  Even naturally sweet raisins contain 59% sugar.

So what's the total amount of sugar in a 30 g serving of "healthy" nuts and berries?  16 grams, or 53%--the same as four mint Lifesavers.

We ended up protecting our child by eating the "yogurt" fruit ourselves.

This snack might be better named "Sugar Cranberry Nut Mix," since it's more than half sugar.  

Ehow article on dissolving candy

I was interested to find an ehow.com article on science projects which references my "Dissolving Hot/Cold" experiment  The author instructs students to use candy such as Smarties, Lifesavers, or M&Ms, and to time with a stopwatch how long it takes the candy to dissolve.  While timing how long it takes candy to dissolve could yield some interesting data, you need to choose carefully what kind of candy to test.  Many candies, including Lifesavers and Smarties, take quite awhile to dissolve.  M&M chocolate will not dissolve in cold water.

If you want to measure how long candy takes to dissolve, I suggest using something that dissolves quickly, like the candy shells on Skittles or M&Ms.  Try timing how long it takes for the color to dissolve off of each piece.  Otherwise, use small pieces of identical candy (I wonder if cinnamon hearts would dissolve quickly).  Avoid doing this experiment with pressed dextrose candy such as Smarties (they take hours to dissolve) or chocolate (if you are trying to compare dissolving times).