Biology: Results are in!

The results are in! With the help of some vanilla ice cream and sprinkles the kids reviewed their results from the Science Fair, and here's what they found:

• Vanilla is detected faster than other flavors.
• Seeing red isn't just an expression. Our scientists found that staring at red raises your heart rate more than yellow or blue.
• Doing exercise decreases the amount of time you can blow bubbles using one breath.
• Listening to rock music was associated with the slowest relflexes.

Of course the results were only half the story. We also discussed sources of error and ideas for next time.

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

Biology: Choosing topics for the Science Fair

This week the kids chose questions to investigate for this year's Science Fair (June 7th 10:00-11:30). The theme for the biology students will be the human body. Over the next few weeks the kids will be working in groups to design, carry out, and analyze pilot studies, the results of which will help them plan the larger scale experiments they will carry out during the Science Fair itself.

Biology: 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
  

Biology: DNA, the Code for Life

This week in Biology we covered A LOT of ground...Phonecian alphabet, pictograms, merits of letter-based writing systems, DNA as code, protein synthesis, and we still hand time for a quick round of Biology Hang-man.

After a quick review of the nuts and bolts of how DNA codes for proteins, the kids did a simulation activity in which they decoded 6 genes into the appropriate amino acid sequences and then drew the resulting organism.

Biology: DNA

This week we started talking about DNA. The kids learned about its chemical structure, focusing on the 4 nucleotides and the rules for complementary base-pairing. Then we made models using clay.

General Science and Biology: Making Crystals

This week we continued our investigations of solutions by making and examining crystals under the microscope. First we made saturated solutions of salt, copper sulfate, and borax. Then we placed a drop of each on a microscope slide, put them outside and waited for them to evaporate, and then used a microscope to look at the crystals that remained.

Pretty cool, but not nearly as cool as the rock candy we prepared. On paper, a very simple operation: Make a really saturated solution of sugar water (3:1) ratio. Heat it on the stove. Then pour it into a jar that has a string suspended inside. Wait a week, and voilà, you've got rock candy. In practice though, it's very messy, sticky, with an extremely low yield. We observed that using a pipe cleaner will produce better crystals because of the increased surface area, but then you might also get brightly colored crystals that not so mysteriously match the color of the pipe-cleaner.

General Science and Biology: Solutions

This week we learned about solutions, that is liquid mixtures. In particular we wanted to know whether water temperature affects how well something dissolves. First the kids compared the time it takes to dissolve a couple drops of food coloring in different water temperatures. Then they tried to see how much sugar they could stir into solution, once again comparing different water temperatures. They concluded that hot water is much more effective at dissolving solutes (that's fancy-talk for stuff).

In the biology group we also noted that the final volume of the sugar solution was surprisingly LESS than the sum of the initial water volume plus the sugar. Part of what happens when you dissolve something is that it reacts chemically with the solvent (fancy-talk for liquid) and/or fits into the spaces within the molecules themselves.

Physics and Biology: How's your aim?

This week we carried out an experiment to test the effects of using one eye or two eyes on depth perception. The kids were given a picture of a target superimposed on a charging rhinocerus.* The target was placed at a distance of 35 cm from the subject, and then he or she had to "shoot" the target with a marker, meaning try to draw a dot at the bullseye. Using different colors for the 3 conditions: both eyes, right eye, and left eye, we were able to score the shots. It was surprisingly difficult to hit the bulls-eye using only one eye, and even when subjects were successful, the kids observed that they were using other cues to compensate, for example how far your arm needs to be extended.

Afterward we did a little comparative anatomy, looking at a skull belonging to a human(we used our own), a horse, a wild bore, and a dog. We observed that in order for depth perception to work, an animal's two eyes must have overlapping fields of vision. We also related these anatomical differences to whether or not animals tend to be predators or prey. Of course, as one student pointed out, this only works when you're talking about animals that use vision in the first place - i.e. doesn't work for bats who hunt using their keen sense of hearing.

*No rhinos were harmed in this experiment

Biology: Which toothpaste works best?

This week we wrapped up our unit on acids and bases by testing which toothpaste works best. The bacteria in your mouth need food to live and multiply. When you eat sugary foods and other carbohydrates, the bacteria use them as food, too. Bacteria in your mouth turn the sugars in these foods into acids that can dissolve tooth enamel (the outer layer of the tooth). Brushing your teeth can help by getting rid of the sugar, but it also functions to reduce the acid-attack on your teeth.

Using chalk to represent teeth (chalk is made of calcium carbonate which is chemically similar to teeth), the kids tested each toothpaste as follows: They set up 4 test tubes, each one with some vinegar, a piece of chalk, and some dissolved toothpaste from one of the brands being tested. Immediately after combining these materials, a balloon was placed over the opening of each test tube. Without toothpaste protection, the balloon inflated as a result of the carbon dioxide produced by the acid-base reaction. Therefore we concluded that the toothpaste that resulted in the least-inflated balloon was the MOST effective.

General Science and Biology: Butterfly Season

Over the past few weeks the kids have been creating butterflies that are camouflaged in different areas of my house. For each one we recorded the date the butterfly went up on the wall, its birthday and the day it was observed by one of my kids i.e. the day of its death.

Check out some of the most well-adapted ones!

General Science and Biology: Purple cabbage broth...more than just just smelly and blue

This week we boiled up some purple cabbage. Why did we do this? Well, it wasn't simply to overwhelm our senses with its powerful smell and uncanny blue color. Cabbage broth has the interesting property of indicating for acids and bases.

The kids added cabbage juice to 7 different liquids and observed the results. They recorded the color changes and using their data from last week, ordered the cups according the pH values. They observed that cabbage juice indicates strong acids with pinks, weak acids with purples, neutrals with blues, weak bases with greens, and strong bases with yellows. Finally they were given an unknown liquid, and using their cabbage-pH scale they guessed its pH.

In the Biology group we took the analysis one step further. After measuring each liquid's pH with the cabbage juice indicator, we explored what happens to the pH of an acid as we add increasing amounts of a base. The kids started off with vinegar + cabbage juice, giving them a nice bright pink, indicating a pH of around 2. As they added more and more baking soda they were able to observe the vinegar change colors as its pH gradually moved closer to a neutral 7.

Biology and General Science

This week we learned about acids and bases and three types of indicators you can use to identify them. We began by using red and blue litmus paper to test different household liquids. We were then able to classify them as acids, bases, or neutral. However while litmus paper is useful, it doesn't tell you anything about how strong or weak a base or acid is. So, for example, while baking soda and bleach, the two bases we encountered, score the same on a litmus test, baking soda tastes mildly bitter whereas tasting bleach will land you in the hospital (hypothetically speaking, of course!). We observed that in order to appreciate this without landing in the hospital, pH paper comes in real handy.

Biology: Makes the heart go pitter patter

This week we talked about homeostasis, the idea that our bodies need to keep things inside more or less the same despite an-ever changing outside environment. Our cells need a certain amount of oxygen, water, and energy in order to function. Furthermore, they can only carry out their metabolic processes within a particular range of temperatures. When we are in situations that challenge the status quo the body must do something to compensate.

This week the kids designed and ran experiments to determine the effects of exercise (loosely translated in some groups as consuming hot chocolate and candy) on breathing and heart rate. Next week they will analyze their data and present their findings.

Biology: Sensational Skin

This week we investigated a type of cell called the sensory receptor. These receptors are found in our skin and allow us to feel pressure, pain, heat, and cold. The kids made pressure probes (see photo), which were used to test 4 different areas of the body: fingertip, forearm, cheek, and calf. The idea was to GENTLY poke these areas with the probe, gradually decreasing the distance between the 2 toothpicks until the subject could only feel 1 prick. The area with the smallest 2-point discrimination was the area that was most sensitive and was assumed to contain the highest number of sensory receptors for pressure. The kids were surprised to find quite a great deal of variation. Subjects could distinguish 2 distinct pricks at an average of 2.5 mm on their fingertips, while the 2-point discrimination was much larger for the calf and forearm - as much as 7 mm.

We concluded by discussing why it might be adaptive for some areas to be more sensitive than others.

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.

General Science and Biology: Which chip is the greasiest?

This week in science we asked the following questions: which brand of potato chip is the greasiest and more importantly, how can I be sure?

We went about answering them by carrying out 3 tests. The first 2 were a touch and a taste test in which the kids rated the chips on a scale from 1-5, with 5 being the greasiest. Then the kids were challenged to come up with a more quantitative test, one based on measurement. Some kids crushed equal amounts of each chip on a piece of graph paper and then compared the sizes of the different oil stains. Others compared the weight of the chips before and after crushing; the assumption being, the greasier the chip, the more oil lost in the act of being crushed on a piece of paper. Another test consisted of soaking different chips in water, removing them, and then comparing the amount of oil observed sitting on top of the water.

After carrying out our tests, we tested our tests. We read the nutritional information on the packages and reviewed our data to see which test was actually the best. Finally the kids thought about how they could improve their tests in the future.

Biology: You must be this small to ride this ride

What does the cell membrane have in common with filters, sifters, and colanders? All of the above are SEMI-PERMEABLE, meaning some substances can pass through them, while others can't.

In this week's experiment we used dialysis tubing (thin layer of material that contains various sized holes) to model the cell membrane. We tied off the dialysis tubing with string to create a bag that we filled with corn starch solution and glucose solution. First we submerged the bag in a jar of water and tested the surrounding water for the presence of glucose using glucose strips. Then we replaced the water with iodine. We waited a few minutes to see if there was a color change in either the bag or the jar. Iodine turns black upon contact with starch, so a color change inside or outside the bag would demonstrate which molecules had traveled through the bag. Check out the picture, and see if you can guess which molecule, starch or iodine can travel through the bag. Hint: Bigger ISN'T better.