Friday, April 30, 2010

General Science: Product Testing, Day 1

This week the kids started work on their Science Fair projects.
Their theme for this year is Product Testing aka "Which _____ is best?"

Step 1: Choose a product to test...anything from lipstick to soap.
Step 2: Define "best" for your product.
Step 3: (Now, for the tough part) Figure out how you will measure this quality for three competing brands.

The kids worked in groups of 1-3 and wrote out research proposals for their projects that they will carry out during chug over the next few sessions.

Biology: Science Fair Projects, Day 1

This week we talked about the kinds of projects the kids will be carrying out for this year's Science Fair. The theme for this group will be the human body. Over the next few weeks the kids will be choosing a question to investigate and then designing an experiment that they will carry out at the Science Fair itself, where (hopefully) there will be no shortage of available subjects.

Physics: Simple Machines

This week the kids reviewed levers and learned about the following additional simple machines: pulley, screw, wheel and axle, and wedge.
REMINDER: In preparation for the upcoming Science Fair, this coming week will be pretty intense....we're meeting Sunday, from 10:00-12:00 (there will be pizza for our budding inventors) as well as our normal meeting time, Tuesday 2:15-3:15.

Tuesday, April 27, 2010

General Science: Plop plop fizz fizz...

After last week's lesson on acids and bases, this week we tested a few different antacids to see which one works best. First we discussed what antacids are and what "best" might mean for an antacid. Then we discussed how we would go about measuring this. The kids ground up each tablet and added it to some hydrochloric acid - that's the same strong stuff you find in your stomach that sometimes causes heart burn. Finally we measured the pH to see which antacid was best at neutralizing the HCl.

This week's experiment was more than just an exploration of antacids. It also modeled the types of science projects the kids will be carrying out for this year's science fair. Working in pairs, the kids will choose some product to test and then design an experiment that will shed light on which of 3 different brands is best by the kids' definition. Stay tuned...

Biology: Ice Cream in a Bag

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

First we demonstrated that ice covered in salt will melt faster than ice alone, and most surprisingly that the liquid salt water is actually COLDER than the frozen ice. We then discussed how phase change, or matter moving back and forth between solid, liquid, and gas states, involves a transfer of energy or heat. In other words, when there is a phase change, heat is absorbed in one direction and released in the other. These ideas and observations formed the basis of our ice cream experiment.

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.


* 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.

Friday, April 16, 2010

General Science: Indicators for acids and bases

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.

Finally we made our own indicator using purple cabbage juice. Cut up some purple cabbage and boil it for a few minutes. The broth comes out this really funky blue color. Try adding it to different liquids - the results are quite dramatic.

Tuesday, April 13, 2010

Biology: Life in the Warsaw Ghetto

This week, biology fell out on Yom HaShoa. I decided that it would be appropriate if we discussed some issues that related both to science and to the Holocaust. We looked at some data on the typical diet of a resident of the ghetto and compared these numbers to the U.S. recommended daily allowance for proteins, fats, and carbohydrates. Then we looked at labels on different food packages to prepare a plate of food that would consist of the daily allotment for a resident of the Ghetto. Afterward we compared the population density of Raanana to that of the Warsaw Ghetto. Hopefully these two exercises helped give the kids another perspective on the suffering endured by the Jews living in the Warsaw Ghetto.

We concluded with a bit of social science: a discussion on stereotypes. The kids were given a list of sentences to complete such as, "All sephardim are...." "All Arabs are.." "All haredim are ..." The kids were given free reign to express whatever stereotypes came to mind. We put everyone's ideas on the board, and then I gave them one last sentence to complete: "All Jews are..." I suggested some of the negative stereotypes of Jews we unfortunately know too well, and as my proof gave a quick summary of the whole Madoff scandal. Many of the kids were upset, pointing out how unfair it is to judge a whole people based on the actions of one person. From there we worked backwards, reexamining many of the other stereotypes we had discussed. We left chug on a hopeful note, observing that while it is natural to group and classify people based on our experiences and knowledge, both of these things may be limited and therefore skewed. Given our unfortunate history of playing the role of the scapegoat, it is crucial for us to constantly be on our guard against harming others through negative stereotypes and discrimination.

Thursday, April 8, 2010

General Science: Chemistry in a bag

The kids started off with calcium chloride, sodium bicarbonate (see if your kids remember this compound's common's baking soda), water, and phenol red, an indicator for acids. They put all of these materials in a plastic bag, the catch being that the liquids (water and phenol red) were first poured into plastic cups, which themselves were carefully placed in the bag.

After closing the bag, the kids allowed the powders and liquids to mix, and that's when things got exciting! The kids observed many changes including: bubbles, the bag inflating, the red liquid turning yellow, and the contents both heating up and cooling down. The real challenge came next when the kids had to figure out which combinations of ingredients caused which results.