Tuesday, November 26, 2013

Chanukah science...spinning tops

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.

This week we talked about how dreidels work and then we observed the optical illusions produced by spinning tops with different colorful patterns. We finished up by making our own tops using old CDs.

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

Chanukah science...Candles, air, and a bowl of water

This week the kids explored the effects of using a graduated cylinder to cover a lit candle standing in a bowl filled with water. What happens and why...these were the questions we set out to discover. Some of the results were easy to spot. Others required repeating the experiment multiple times.

Tuesday, November 19, 2013

Cells, up close and personal

This week we continued our investigations with microscopes. Having already gotten some experience last week with the ins and outs of using one, we focused on cells. The kids got a chance to compare plant and animal cells by extracting human cheek cells (sounds much more painful than it actually is) and onion cells (a little smelly, but otherwise no tears). We talked about how animal cells are more "blob-like," and how plant cells have a rigid exterior, which makes them look like boxes or bricks. 

Afterward the kids looked at other specimens under the microscope including: a mosquito (the wings are really interesting up close), a spider (much hairier than you'd think) , a louse (even scarier magnified 100X), a blade of grass, and various leaves.

Whisper words of wisdom, letter "e"

This week we learned how to use a compound microscope. First we reviewed the parts of a microscope and what they do. Then the kids learned how to prepare a wet mount (a slide with a specimen + a drop of water and a cover-slip) The first specimen the kids examined was a lower case "e." When it comes to the letter "e," there's more than meets the eye. It doesn't just get bigger...

After we got the hang of things, we looked at some serious specimens. If you think spiders are scary, try looking at one magnified 400 times!


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 .


The daffodils we planted in the yard are just starting to emerge from the ground. We can see a few tiny shoots. On the other hand, the bulbs growing inside show visible changes day-to-day. That's why we decided every kid should have a bulb of his own to plant and observe at home. Weekly observations just aren't enough! The kids made special diaries, "daffodiaries," to keep track of how their bulbs develop.

You can plant a daffodil outside in the soil, but we decided to "force" our bulbs to grow indoors without soil, so that we could better observe the changes.  The downside of doing it this way is that the daffodils will take in fewer nutrients for NEXT year's growth. With the exception of water and sun, everything the flower needs is already packed inside the bulb.

With that in mind, here's what we're going to do when we get home:
  1. Find a small glass bowl. 
  2. Fill it with some rocks, marbles, legos, etc. 
  3. Place the bulb on the rocks/marbles/etc. pointy side up.
  4. Pour just enough water into the bowl, so that ONLY the base of the bulb is under water.
  5. Leave the bowl in a sunny spot, and wait and see.
Within a day or two we hope to see roots, and not long after, a shoot coming out of the top. We just need to make sure that the roots have water, and that the plant gets enough sun.