Physics and Biology: Dry Ice

Dry ice is unlike the ice we know and love. It's frozen carbon dioxide, and it's called "dry" because it passes from the solid phase directly into the gas phase, skipping the liquid phase entirely, resulting in some AWESOMELY weird and funky behaviors! It's CRAZY-cold, so cold in fact, we only handled the dry ice with a towel or tweezers....NEVER with our bare hands!

We demonstrated its COOLNESS in the following ways....

• froze cooked pasta and flowers by dropping them in acetone with dry ice. (Acetone is good thermal conductor, so it gets really really cold.)

• produced a lot of spooky fog.

• "poured" carbon dioxide gas into a cup on a scale and noted that it weighed more than an equal volume of air.

• used carbon dioxide gas as a fire extinguisher (Don't panic, the fire was a single lit candle).

• made long-lasting carbon dioxide bubbles by adding dry ice to soap solution.

• made the dry ice "squeal" and vibrate after pressing it with a metal spoon.

• inflated a balloon by putting a piece of dry ice inside and then tying off the open end.

Physics: Danger...QUICKSAND!!!

Today the physics group was challenged to figure out the best way to escape from quicksand. To thrash or not to thrash? Before jumping to any conclusions our young scientists decided to model the problem using "ooblek," a mixture of cornstarch and water. Like quicksand, ooblek changes quickly from solid to liquid as a result of changes in pressure making for some really strange behaving goo!

First the kids made their own ooblek - 2 parts cornstarch to 1 part water. Then to be sure it was just the right consistency, we applied the "slap and splash test." If you slap it and it splashes, too much water. If you slap it and nothing happens, you done good! For the most part,there were no casualties, and our scientists proceeded to figure out the best way to exit the quicksand experimenting with plastic animals and action figures. Their recommendation: Don't panic and move slowly.

Corrections

My fact checker (my husband) has just informed me that all of the Sharper Image stores were closed by the end of 2008 after bankruptcy.

Take the SCIENCE IN MOTION Challenge!

Today being the last day of science, seemed like a good time to do the Science in Motion Challenge. The Science in Motion Challenge has two parts: a series of questions relating to the experiments carried out over the course of the year and a few fiendishly difficult science dares including:

• Float a paper clip in water.
• Insert a sharp pair of scissors into a soap bubble without popping it.
• Have a catch with a bubble without popping it.
• Make soap bubbles that are shapes other than spheres.

Armed with their intellect, a sense of adventure, and their lab notebooks, the kids made short work of the questions, the dares, not to mention my back yard!

It's been a great year - I really enjoyed working with your kids!
Have a wonderful summer!

Rebecca

Science Fair 2010

This year's Science Fair was a big success! Our general scientists did some excellent product testing, the physicists' inventions will no doubt be lining the shelves next year at Sharper Image, and the biologists planned and executed some fascinating projects on the human body.

Here is a quick summary of the results from the biology projects:

• Spinning with your eyes closed made you dizzier than with your eyes open.
• Doing exercise slowed down drinking capacity, more so with water than with coke.
• The effects of static electricity were observed the most in people with wavy hair.
• The right hand of righties was more sensitive to temperature than was their left.
• Boys had greater lung capacity than girls.

Our scientists had a lot more to say than just the bottom line, so please ask the kids about the challenges they faced carrying out projects with human subjects.

Kudos to all our budding young scientists as well as their supportive families and friends!

Biology: Got Milk??

This week we did one of my favorite kinds of experiments, the kind that ties in pretty much everything we've been learning about all year: chemistry, enzymes, genetics, evolution...You name it, we've got it! We started out by testing the effects of adding lactaid to milk. Using glucose strips we showed that lactaid causes the lactose in milk to break down into simpler sugars such as glucose. Lactaid is a substitute for lactase, the enzyme that mammals use to break down milk.

So far, so good....but where's the drama?! After understanding a bit about the chemistry, we looked at milk digestion in the context of human evolution. No more simulations, no more flipping coins. Instead, we took a real-life example, and one that relates to our own species. In MOST humans, as is the case in most other mammals, babies STOP producing lactase around the time they are weaned. What this means for most mammals is that drinking milk post-infancy causes stomach problems. Yet among some humans - perhaps, you know one of these mutants?! - eating milk products throughout their life is done happily with no side effects.

What made these mutations persist in certain populations and not others? The strong correlation found between populations whose ancestors hung out with cows and sheep with populations with a high frequence of lactose TOLERANT individuals suggests that the distribution of this trait is the result of some serious natural selection. Having the ability to digest milk, particularly during cold winters when others food sources were scarce gave people with this mutation a real advantage, which they in turn passed down to their kids.

So if you're one of those people who use a pint of Ben and Jerry's to take the edge off a bad day, now you know why.

Physics and General Science: DIY Ice Cream Maker

This week we did a pretty COOL trick....we made ice cream, without a freezer, using our own DIY ice cream machine. How did we do it and what does it have to do with science?

The kids poured the ice cream ingredients (milk, vanilla, and sugar) into a small plastic bag. Then they placed this bag into a larger bag filled with a lot of ice and a lot of salt. The whole business was then wrapped in a towel and then shaken until the milk mixture solidified. The rock salt caused the ice to melt quickly and reach a sub-zero temperature, so that the resulting freezing salt water could quickly absorb heat from the milk mixture, giving you yummy, delicious ice cream or at the very least, a super-cool milk shake.



Here's the procedure in case anyone wants to try it at home.

1. Pour ¼ cup of milk into a sandwich-size zip lock bag.
2. Add 1 teaspoon of sugar and a couple drops of vanilla extract.
3. Close the bag carefully, while getting rid of the extra air.
4. Mush the bag around to mix the contents.
5. Place this bag in another sandwich zip lock bag, remove the extra air, and seal.
6. Fill a 1-gallon zip lock bag with ice and a half a cup of rock salt.
7. Place the double bagged milk mixture inside the larger bag, squeeze out the extra air, and seal.
8. Wrap each bag in a towel and mix, shake, and churn until the inner bag's contents freeze.

Tips:

* Make sure all bags are closed, especially before you start shaking up the bag of ice and salt.
* Double-bagging the milk mixture is important, to help reduce the odds of salt penetrating the bag and getting into the ice cream (yuck!).
* Err on the side of too much ice and too much salt.
* Try to keep the milk mixture bag in the middle of the ice, and especially in the middle of the melted salt water.
* See what happens if you add different flavors like chocolate syrup or lemon juice.

General Science: Genetics with a smile

This week the kids carried out a simulation in which they explored how traits are passed down from one generation to the next in the strange but cheerful species, commonly known as "smiley faces." The kids flipped coins to see which genes the smiley faces would pass on to their offspring. While the kids observed several differences between smiley faces and us - e.g. smileys have eyes that are shaped like stars (maybe that's why they're so happy?), we also noted the basic principles of inheritance we share.

• individuals carry 2 versions of each trait, one from the mom and one from the dad
• individuals pass one 1 version of each trait to each offspring
• an offspring's phenotype (what he looks like) is the combined result of the 2 versions he got from mom and dad - sometimes, but not always following the rules of dominance
  

Physics: Triangle Appreciation Day

Last week we carried out a few experiments demonstrating the power of the triangle. The kids built squares and triangles out of straws and tested them to see which shape is more stable. Triangles won, and they used this fact to strengthen a 3-D cube made out of modeling clay and toothpicks and then cubes made out of straws and paperclips.

Check out how strong this cube is – that's some seriously HEAVY material!

Biology:The birds and the beans

Building upon what the kids already know about adaptation, we began to discuss natural selection. If individuals with one version of a trait are fitter than individuals with other versions of the trait, what happens to the distribution of this trait in the population over time?

To understand this concept, we carried out the following simulation. A lab group was given 50 red beans and 50 white beans, representing the parent generation. Each group worked in 1 of 3 different environments: the white floor, the red sidewalk, and the green (very green - oh how I love my astroturf!) grass. One kid/bird from each group would hunt for 75 beans, and then the 25 remaining survivors would reproduce, having 3 offspring, each one the same color as the parent. The kids repeated the simulation 2 more times, and then observed the long-term effects of living in a particular environment on the frequency of red and white beans in the population.

As for the results, they don't call 'em bean counters for nothin...all that counting takes a lot of time. Next week we'll review and discuss our findings.

Biology: Hunting etiquette

Which fork should you use...depends on that you're hunting!

This week we learned about adaptation. We decided to test which hand adaptation: fork, knife, or spoon would be best at hunting different types of prey such as marbles, rubber bands, and hair clips. These items were spread out on the grass, and the kids, with the help of forks, knives, or spoons went hunting. We found that spoons were best overall, but when it came to catching rubber bands, knives won hands down.

We concluded that there is no "perfect" adaptation. What works well in one environment may be less effective somewhere else.