Chanukah science...Which oil is the most miraculous?

In anticipation of Chanukah we investigated different oils and candles to see which one burns most efficiently.* We tested each oil or candle by measuring the mass before and after letting the wick burn for 3 minutes  We concluded that the one that lost the LEAST weight was the most efficient fuel source, and also the most miraculous.

*inspired by Amitai Levy and Roey Roth's 2008 science fair project

Catapults

This week the kids were challenged to reverse engineer a catapult. Presented with some old broken catapults, the kids had to figure out how they were made. Then, using slightly different materials, they modified and improved this initial design to produce catapults of their own. These catapults are examples of a 3rd class lever .

Seesaws

This week we started talking about simple machines. The first machine we looked at was the lever. After discussing the 3 classes of levers and examples of each, we experimented with a class 1 lever, the seesaw. Each lab group was given a pair of unequal weights. The goal was to figure out how to place them on the seesaw, so that they would be perfectly balanced. In each case we recorded the distance from the fulcrum. After trying out several different pairs, we reviewed our data and looked for patterns.

Let's see how much YOU know about levers...If you place a 500 g weight 10 cm from the fulcrum, where do you need to place a 100 g weight so that it will balance the heavier weight?

Catch me, I'm falling!

Why do some objects fall faster than others?

We reenacted Galileo's experiments in Pisa to test whether an object's weight influences its speed. After a quick trip up the Leaning Tower of Raanana (aka my stairs) like Galileo, we concluded that weight DOESN'T matter, and that how fast an objects falls is the result of an object's air resistance, i.e. the friction between the object and the air as it moves.

From there we naturally moved on to the subject of parachutes, objects specifically designed to maximize air resistance to keep jumpers from hitting the ground too fast. We dropped balls of modeling clay with and without home-made parachutes and compared flight times and the effects of hitting the ground on our jumpers.

See this TED ED talk for a great way to think about gravity

As an extra bonus this week, we also caught the solar eclipse. Thanks to my husband, Danny for the heads up about the eclipse and for showing us how to safely project the image of the sun on to a white board using binoculars. Of course, you should NEVER look through a telescope or binoculars to point them at the sun. Doing so can result in partial or total blindness.

Slip sliding away

The kids took what they had learned previously about friction to the field. We spent the first half of the lesson planning out a controlled experiment to compare the "slidability" of different materials. Then we walked to Park Mapu, where the kids worked in groups measuring the time it takes to go down the slide on a range of materials including: a towel, a piece of card board, and a fleece blanket.

Slippery Slope

Which surface has the most friction with a coin?
To figure this out, we placed a coin on top of different materials, gradually raised one end of the material until the coin began to slide, and measured the angle using a protractor. The idea being, the steeper the angle necessary to get the coin moving, the greater the friction between the material and the coin. 

Next week we hope to apply our results to the larger question: What can you do to reduce the friction on playground slides? Let's hope for good weather!

The Tortoise, The Hare, and You!

Usain Bolt is unquestionably the fastest human alive, but how would he do if he had to compete against other species, like say a grizzly bear? In 2009 he broke the world record, running 100 meters in 9.58 seconds. That's faster than 10 m/s and around 38 km/h. This week we looked at some data on the maximum speeds of different animals and then tested our own local humans.

Most of us fell somewhere between a chicken and a pig.

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)

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.

SCIENCE TNKERS...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 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.