Saturday, December 31, 2011

Building a Bigger Pyramid - Marshmallow and Toothpick Tetrahedrons Take II

I had every intention of posting a number of video links, and book recommendations to round out, and finish off our "chocolate week". But, what started out this morning, as a quick and easy boredom buster for the younger children...

...turned into a full scale family building project... the older children joined in, to end out the year in an effort to outdo...

...A's marshmallow and toothpick Sierpinski inspired creation from the first of the year.

It took all day, two bags of marshmallows, and somewhere around five boxes of toothpicks, but we did it!

Unfortunately, one of our tetrahedral towers proved unstable, and before I had even finished snapping photos...

...we realized our pyramid was becoming a kinetic sculpture.

That proved to be entertaining, too.

Eying the destruction, we realized it really was only one of the structures that had failed.

And, with some quick work we were able to rescue the other three.

The younger children want to fix up the failed tetrahedron, too...

...but they have they have quite a bit of work ahead, enough at least, to last us into the new year.

It's great to be a homeschooler.

Friday, December 30, 2011

Kitchen Rheology for Kids, or Watching Chocolate Melt

Chocolate is a complex, non-Newtonian, emulsion of fine, semi-solid particles suspended in a polymorphic fat. Which basically just means, in addition to it being delicious, it's a lot of fun to watch it melt.

Depending on the chocolate, and the level of cocoa butter it contains... might pool into a molten puddle as you heat it...

...or it might hold its shape...

...until it's touched.

And, sometimes it can be really surprising to see which chocolate candies will do which.

So far, we've found the slices of our chocolate orange melt into a pool, as do squares of bittersweet chocolate, Hershey Candy Cane Kisses, and even our baker's chocolate (which says on the package it will hold its shape while melting), while dark chocolate Hershey bars, our chocolate Christmas coins, pretty well all of our chocolate chips, and Hershey Milk Chocolate Kisses hold their shape after they are melted until they are touched.

It's great to be a homeschooler.

Thursday, December 29, 2011

Left Over Christmas Candy Science Experiments - Part 4: Blooming Chocolate

Another thing we learned about chocolate this week, is that is can bloom. In fact, we found some blooming, right in our own cupboard. See the white film on the baker's chocolate below? It's called fat bloom, and is caused when chocolate has been stored at temperatures above 75 degrees Fahrenheit, allowing the cocoa butter to separate from the solids, and rise to the surface of the bar.

If you rub fat bloom, it will feel greasy, and will melt, or appear to rub off. The magnified picture below on the left is of the chocolate before it was touched, and the picture on the right is after the bloom was wiped off. If I understand correctly, the light brown spots are the cocoa butter.

We tried to produce this same kind of bloom on some of our chocolate coins by melting them, and then allowing them to cool overnight.

Our results were less than impressive, until we melted the chocolate again, stuck it in the freezer to harden, and then let it sit out on the counter. Our chocolate bloomed alright...

...this time with a sugar bloom.

Sugar bloom occurs when chocolate is stored in a humid environment, or when it "sweats" as it is brought from a cold storage, such as the freezer, into a warm room. Condensation beads on the surface of the chocolate, and draws out the sugar. When the water evaporates the sugar is left crystallized on the surface of the chocolate.

It appears grainy, and can't be rubbed off...

...and is incredibly interesting to view through a handheld microscope. You took my advice last year, and picked one of those up, right?

According to the labeling on our box of baker's chocolate, blooming does not hurt the taste or quality of the chocolate. There are many who disagree, and advise against using bloomed chocolate. My children however, found it to be just fine, except for the baker's chocolate - which of course, I let them taste, too :).

For an excellent, but easy to understand, scientific explanation chocolate bloom, as well as a great diagrammed explanation of the purpose of emulsifiers in chocolate, check out this post from Bite-Sized Biology.

It's great to be a homeschooler.

Left Over Christmas Candy Science Experiments - Part 3: M&Ms

Melting chocolate yesterday, made us think of M&Ms, and their claim to "melt in your mouth, and not in your hands". Naturally, we had to check out the validity of the claim.

We cut open an M&M, and observed the thin candy coating around the chocolate center. Then, we placed the M&M with a few others into a bowl...

...and used a blow dryer to heat the M&Ms, keeping track of the temperature with a candy thermometer.

At around 100 degrees Fahrenheit (we were aiming for body temperature - the temperature an M&M would be at in your hand, but it's difficult to be accurate with a blow dryer), we poked the chocolate with a toothpick. It was melted, but the candy shell was not.

In fact, the candy shell did not melt even when we increased the temperature (by moving the blow dryer closer to the bowl) to 200 degrees Fahrenheit, the temperature at which we found a Lifesaver candy would begin to melt.

Clearly, the heat of your hand will not melt the candy shell of an M&M. Rather than melt, the candy coating dissolves when it comes in contact with moisture (which is why if you have sweaty hands, all bets are off).

To check our thinking, we poured a small amount of cold water (we were curious to see if temperature mattered) in a bowl of fresh M&Ms.

The candy shells started to dissolve immediately.

Finally, we poured enough water into the bowl to completely cover the candies, so we could watch the edible M stickers float to the top, which is pretty cool!

It's great to be a homeschooler.

Wednesday, December 28, 2011

Left Over Christmas Candy Science Experiments - Part 2, Seizing the Chocolate

When melted chocolate, like say a few of those chocolate coins from the children's stockings stuck in the microwave for 30 seconds and stirred (or melted on top of a heat pad, if you prefer)...

...comes into contact with water, even a little water, like a single drop from a clean straw, it seizes, or clumps up...

...just like sugar on the back of a wet spoon. It happens for pretty much the same reason, too. Although melted chocolate is in a liquid state, it doesn't contain water (I'm not actually sure about the chocolate coins, but pure chocolate doesn't have liquid in it), so the solid bits floating in the fat are drawn to the water, causing the entire batch to clump up (or something like that).

Of course, if you dip the sugar clumped spoon into your tea, the sugar will dissolve just like normal. The same is also true for the chocolate. You can't melt it back to normal, but you can "save" it, by mixing it into a liquid, such as warm milk. The rule of thumb is 1 teaspoon of liquid for every ounce of seized chocolate.

In our case, we found with a little stirring, 3/4 cup of milk was just about right for turning 5 or 6 coins worth of seized chocolate...

...into something pretty good to drink.

It's great to be a homeschooler.

Tuesday, December 27, 2011

Left Over Christmas Candy Science Experiments - Part 1

I don't know about you, but we have an obscene amount of left over Christmas candy in the house, right now. The children are determined to do their best to eat it all, but I'm hoping to sidetrack at least some of their snacking schemes with a few fun filled, candy themed, science experiments.

I've been wanting to try exploding a chocolate covered marshmallow creation in the microwave, with the children, since seeing a similar demonstration, with left over Halloween candy, in a Science Sunday post from The Hmmm...schooling Mom.

After a quick review, for the younger children, of what happens to both chocolate chips, and marshmallows in the microwave (and why)...

...we were ready to move on to theorizing about what would happen to our chocolate covered Santas. Most of the children thought the melting chocolate would mix with the melting marshmallow as it expanded, and form a gooey brown mess.

When I pointed out to them, that the chocolate chips had held their form, even when melted, until touched, a few of the children decided that the expanding marshmallow might crack and burst through the chocolate layer.

Interestingly enough, the marshmallow did burst through the chocolate, ripping it apart down an even seam, and folding the chocolate back, as the marshmallow expanded...

...leaving all the chocolate melted underneath the gooey marshmallow remains... which point, the children remembered their determination to eat all of their remaining Christmas candy, and decided to slip graham crackers under the last few Santas, before popping them into the microwave for 15 seconds, what they found to be the optimal melting time...

...for perfect, melted candy s'mores.

It's great to be a homeschooler.