General Science and Physics: 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...

• compared "dry ice" to regular "wet ice"
• 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.

The COOLEST thing we did was toasting a fantastic year of science with home-brewed soda.

Here's the recipe:

1. Pour juice into a pitcher

2. Add a block of dry ice

3. Enjoy the show as you down your cold, carbonated fruit-flavored soda!

Science Fair

General Science:
Market Research Projects….Which ______ is the ______est?

In these projects the kids were challenged to compare everyday objects through the lens of scientific evaluation. To determine which object was the best for a particular category the kids had to define best in some way that could be measured and then set up conditions that allowed for a fair competition. This is the method used by all scientists regardless of their questions.

Physics: Inventors’ Workshop

Over the past few weeks the kids have attempted to design and build an invention that contains a lever. We agreed up front that it was unlikely that any of our inventions would “succeed” in the traditional sense of the word. After all, most inventors spend thousands of hours imagining, designing, building, failing, and restarting the process again and again. When you look at these projects, you should see them as a sort of diary of the kids’ dreams and their initial attempts to actualize them. Trial and error plays a role in the creation of every great invention. Here is a window into this process.

Biology: Human Body Projects – thanks for volunteering

Working with people is never easy. Working with human subjects even less so. Part of what we discovered this year in biology is the complexity and lack of predictability you get with all living things. Whether it’s microscopic organisms in pond water or human size ones in my backyard, bottom line is it takes a lot of patience, planning, and careful observation to design and carry out an experiment with human subjects. The biology kids first did their experiments on each other. After analyzing their results they modified their experiments to arrive at what you see here today.

Making ice cream with salt without making salty ice cream!

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.

Science Fair coming soon!

Haven't written an update in a while, because as of May my job has changed somewhat. Whereas I uses to design the experiments, now the kids have taken over, and I have become their humble lab assistant, here to provide space and materials for the experiments they are designing themselves. These projects will be on display at this year's Science Fair. It will take place June 7th (Erev Shavuot) at my house from 10:00-11:30. Family and friends are welcome!

Here's a preview of what to expect.

General Science: Product Testing/Market Research…

"Which _____ is the _____est"

Find out the answers to questions such as which toothpaste is the best, which cream whips up the most, which permanent marker is the hardest to remove, and which type of soda makes the best mentos explosion!

Physics: Lever-based Inventions...

"Give me a place to stand, I will move the Earth"
Get a rare view of cutting edge technology at various stages of development.

Biology: Carrying out Experiments in REAL TIME…
You and yours get the chance to be subjects in these experiments on the human body.

See you there!
Rebecca

Physics: Mirror mirror on the wall

This week in physics the kids completed their periscopes and carried out some experiments with lenses and mirrors. In the first experiment the kids placed an object in front of a set of hinged mirrors. The kids observed how changing the angle between the two mirrors affected the number of images produced and tried to figure out the pattern. Then the kids examined a bunch of different lenses, some convex and some concave and noted how looking through each one affected the size of magazine print. One of the lenses they tried out was a drop of water. Convex or concave...what do you think?

Physics: Periscopes

This week the kids built periscopes.

Physics: Bridges

This week the kids built bridges out of straws. Given 20 straws and some tape, the kids were challenged to build a bridge spanning 25 cm that would hold the maximum weight.

Physics: Bridge Basics

This week the kids built bridges out of index cards. They could bend or cut the cards anyway they liked, but the bridges had to span 10 cm, with no more than 1 cm at either end resting on the supporting books (once again an incomplete set of 1985 Encyclopedia Britannica comes in handy).

We tested the bridges to see which ones could support the most weight. The simplest flat bridges could hold around 30 g, while bending the card into a fan-like structure could support more than a half a kilo. Pretty cool!

We concluded by discussing how bridges and other structures often feature triangles because of their ability to transmit forces of tension and compression.

General Science and Physics: The Shadow Knows

This week we observed what happens to outdoor shadows produced by the sun over time. The kids worked in pairs repeatedly tracing each other's shadows, however always from the same starting position. We were all pretty surprised to see that even over a short period of time, in the late afternoon our shadows grew and changed in position.

In physics we took this one step further and used what we learned to make sundials. We built them out of straws mounted on plates. The kids brought them home and set them up in spots that get a lot of sun, so that they will be able to trace the straw's shadow at different times over the course of the day.

Physics: What is density anyway?

This week we explored what density is. We started with a comparison of STUFF vs SPACE (i.e. mass vs. volume). Then we measured the mass and volume of 6 different objects. Measuring the mass was pretty straightforward...we used a scale. Measuring volume was a different story. To measure the blocks we used a ruler to measure each dimension and then multiplied them together, and for the irregular-shaped objects, we dropped them in a graduated cylinder filled with water and recorded the subsequent change in volume. Now for the HARD part! To get an idea of just how much STUFF is in a given amount of SPACE, we calculated the density by dividing the mass by the volume. Finally we put each object in water and noted whether it was a sinker or a floater. The coolest part was noticing that the density of all the floaters was less than 1 g/ml and the sinkers were all greater than 1 g/ml, and from this we inferred the density of water - 1 g/ml.
Not an easy lesson, but hopefully it will eventually SINK in!

Physics: Depth perception in basketball and football

This week the kids designed and executed an experiment to investigate whether two eyes are better than one when it comes to football or basketball. This lesson was a follow-up to the lesson we carried out two weeks ago, in which we carried out some mini-experiments on depth perception. Reflecting on the difficulties and challenges that came up during these experiments allowed the kids to write a more well-thought-out and developed experimental design for this week's experiment.

All groups found that on average a subject's game was improved with the used of two eyes over one.

Physics: Luke...it's your density

This week we began an investigation of why things float and sink. We looked at a couple different set-ups and made observations. The first thing we looked at were some raisins in a glass of seltzer. What was odd about the raisins was that sometimes they floated and sometimes they sunk. It took a while to figure out what was going on, but then we noticed that the raisins would initially sink, and then after collecting some bubbles from the soda, would take a ride to the top. The second set-up was a simple lava-lamp-like device. Some water, some oil, and then to literally spice things up, we added salt. Globs of oil that had been previously sitting on top of the water were dragged down by the sinking salt. As the salt separated from the oil, these globs would then race back to the top. Finally, the kids filled test tubes with 3 different liquids: water with food coloring, corn syrup, and oil. They observed the layers that formed and then tried adding them to the test tube in a different order to see if that made a difference.

Next week we'll discuss these observations more and try to understand what's going on.

Physics: Two eyes are better than one

This week we investigated depth perception, the ability to perceive the world in 3 dimensions. We carried out a few tasks that require depth perception, and compared a subject's ability to do them with one eye vs. two eyes. For the most part, we found that depth perception requires the use of two overlapping fields of vision, i.e. two eyes as opposed to one, with the two eyes being located along side each other. After discussing our results, we talked about some of the challenges involved in comparing the use of one eye vs. two eyes. Next week the kids will design an experiment to test whether one uses depth perception in a game of catch. Hopefully the kids can use some of their critiques from this week to help them design a fairer and more controlled experiment next week.

Physics and Biology: Newspaper Skyscraper

This week the kids were challenged to build a skyscraper out of newspaper and tape. The question was: how do you use such a flimsy material to build something that is both tall and able to withstand powerful winds. Through trial and error the kids learned that they could increase the strength of the newspaper by rolling or folding it in different ways as well as that building a wider/heavier base makes the tower more stable.

Afterward the kids evaluated each tower by measuring its weight, height, and stability in the face of a powerful blow dryer. One of the things we observed was that different designs privileged one characteristic at the expense of another. A building that was particularly stable was also quite short. In Biology, we noted that this is characteristic of the natural world as well. An organism may have traits that make it well-adapted to one environment, while poorly adapted to another. We will revisit these concepts later this year when we cover evolution.

Physics: Stopping on a dime

This week the kids used their physics skills to solve an engineering problem: Say you want to build a new basketball court, how much room do you need, besides the court itself? To figure this out the kids collected data on their reaction time, running speed, and the distance you run past the finish line, as you try to slow down.

We decided to consider the slowest reaction time, the fastest speed, and the longest overshoot in order to come up with a safe and conservative estimate for the distance between the out-of-bounds line and other obstructions. The kids observed that most people can't stop on a dime, particularly not during a competitive sport like basketball, and based on our data suggested a minimum distance of 2.5 meters between the court and any walls or obstructions.

Physics: Good Vibrations

This week we talked about what a sound is and experimented with sounds produced by different materials. The kids made oboe-like straws, plucked rubber bands of different widths and lengths across shoe boxes, bounced wooden sticks off the side of tables, and struck glasses filled with water (looks like wine, but it's just food coloring, I promise!), noting in each case how different changes affected the pitch. Finally, the kids used their observations to created their own instruments, and then we had a concert!

Physics: What color is it really?

This week we did 3 mini-experiments to investigate how we perceive color. The first was with spinning color wheels. The kids compared the patterns of the discs when still to the patterns they saw when the discs were spun. The second mini-experiment involved looking at magazine pictures under the microscope and comparing the images seen with the naked eye to the colors seen at greater magnification. The third was simply giving each kid some red, blue, and yellow paint and letting them go wild...well on paper anyway.

When we physically combine red, blue, and yellow paints in different proportions we can create an enormous range of colors. Similarly the human brain will combine colors that your eyes see when those 2 colors are seen in rapid succession, as in the case of the spinning color wheels or when they are placed very close together, as revealed by a microscopic examination of pictures from a magazine. What is especially cool about the magazine pictures is that no matter what color you "see," when examined under the microscope you realize that the image is made up of just 3 colors: magenta, cyan, and yellow (aka red, blue, and yellow). By producing images that include different ratios of the primary colors, you can get just about any color.

Physics: You spin me round round...

What do bicycles, frisbees, yo-yos, hula hoops, dreidels, and even the earth have in common? They all spin, and so long as they spin the better they are at resisting what gravity is trying so hard to get them to do, which is tumble and fall. The tendency of an object to resist change, is called inertia, or in the case of something spinning, rotational inertia. This week the kids were given plastic plates of different sizes, sticks, and weights (in the form of kippa clips) and were challenged to design the dreidel with the greatest rotational inertia...that's fancy talk for the dreidel that can spin the longest.

Physics: Magnets

This week the kids investigated magnets. They tested various materials to see which ones are magnetic, compared the strengths of different magnets, learned how to turn iron nails into weak magnets, observed the effects of magnets on compasses, and used iron filings to observe magnetic fields.

Physics: Quiz-show Part II

This week the kids finished their quizboards - hopefully by now you've seen them, played with them, and hopefully not broken them! This was NOT an easy project. It took a lot of patience and attention to detail, checking and rechecking connections in the circuits, but in the end it paid off. "Operation's" got nothing on these quizboards.

If you haven't already, please register your kids and send in checks asap. Kids who aren't fully registered by next week will have to work off their debt at the Large Hadron Collider, tracking the subatomic chaos of protons colliding 300 feet underground in the bowels of this giant particle detector.