Un-mixing Milk

This week we tried 2 different ways to "un-mix" milk. The first way involved brute strength! We poured some heavy cream into a jar, and we shook it and shook it until it separated into a clear liquid and a creamy solid, better known as butter.  The second way we extracted solids from the milk was through a few chemical reactions. First we added some vinegar to the milk to curdle it. Then we separated the solid proteins using filter paper, and neutralized any extra vinegar with baking soda.  Finally we added a little water, resulting in our own home-made glue.  

From the Earth to the Moon

This week we got the following challenge: Apply Newton's 3rd Law: For every action, there's an equal and opposite reaction, to design a rocket that can travel from the earth to the moon, or at the very least, design a straw, souped up with just a balloon and tape,  that will fly along a string, tied between two chairs sporting pictures of the earth and the moon. We worked in teams designing, building, and rebuilding our rockets. We learned a lot through trial and error and were even inspired to brainstorm how to design a balloon rocket that would travel to the moon and back in one uninterrupted trip. 

What would you do?

Here in Israel, we've got some real heroes to inspire us. Yariv Bash, Kfir Damari, and Yonatan Winetraub are leading Israel's SpaceIL's team in Google's global competition to successfully launch, fly, and land a robotic spacecraft on the moon.

For some more background on their work, you can watch this BrainPOP video.

"We choose to go to the moon this decade and do the other things, not because they are easy, but because they are hard"(John F. Kennedy, 1961)

Measuring Mass

This week we added the triple-beam-balance to our repertoire of measuring tools. First we discussed the difference between volume and mass, and then we worked in pairs guessing and weighing different objects. Finally we checked ourselves and the triple beam balances using a digital scale. We noticed that a) we measured pretty consistently, and that b) our triple beam balance was only off by about a toothpick. Not that big a deal, unless of course, you're measuring toothpicks!

So what do you think weighs more...a pound of gold or a pound of feathers?

Etrog vs. Lemon

With the holidays just wrapping up, studying etrogs from a biological perspective seemed like a great way to kick off Science Explores aka Life Science. The etrog, more commonly known as the citron, belongs to the citrus family of flowering plants. Etrog trivia: The "pittom" is which part of the flower?1

Then we asked the question: Is an etrog simply an over-priced, funny-shaped lemon, or is there more going on?2 We made some external observations, noting their shape, color, volume, mass, and density. Then we opened them up and looked inside. Turns out, there are some interesting differences in the relative proportions of peel, fruit, and juice volume. We measured each fruit's pH, and then celebrated a job well-done to the tune of a tall glass of lemonade. Due to the lack of juice, the etrogade wasn't as successful.

More ETROG TRIVIA...
"Flavedo" and "albedo" are
a. the yellow and white parts of the rind
b. trapeze artists, as in "The Amazing Flavedo and Albedo"
c. great scrabble words, well "flavedo" anyway
(3)

Answers
1. The stigma, the part that receives pollen grains
2. There's more going on 
3. a.

Go Speedracer Go!

It's just amazing what you can learn using the Encyclopedia Britannica. In fact if you stack 4 or 5 of them, you can build a pretty cool ramp, great for exploring the concepts of motion. Get a couple of toy cars and you're ready to roll! Measure the length of the track, how long it takes each car to reach the bottom, and you've got everything you need to calculate their speed.

Always chasing rainbows

This week during science the kids got A LOT of practice using a graduated cylinder. Each team had to follow very specific directions for adding and subtracting precise amounts of red, blue, and yellow water to produce a beautiful rainbow of colors. Afterwords we discussed possible sources of error including: spilling, not following directions, measuring incorrectly, and in this case, the starter blue water being too dilute, accounting for the strange greenish color all the groups got instead of purple.

Just for fun, estimate the volume of...

* a mouthful of water
* cup of apple juice
* a kiddush cup
* water used in your average bath

Then check yourself with a measuring cup. (This experiment was conceived during dinner one night when one of my kids INSISTED that the other one got more juice...)

Milk Mixer

What happens when you add a few drops of food coloring to water? What about milk? If you're in the mood for some psychedelic action, see what happens when you put some soap on the end of a toothpick and gently touch the surface of the milk.

We got off to a great start this week exploring these questions. First the kids had to learn how to measure liquid volumes using a dropper and a graduated cylinder. Graduated cylinder's kinda tough to say, but we counted, and it's still one less syllable than fancy schmancy measuring cup, so we all agreed to use the more scientific term. And of course, like all good scientists, we recorded our observations, results, and conclusions in our notebooks.