We are on Passover Break until Friday, April 10th. We will return to the office Monday, April 13th at 7:00 a.m. All inquiries and questions submitted through the website will be answered on Monday the 13th. Thank you!
This week in Science we learned about moiré patterns and kinegrams.
First we looked at the shadows of two combs projected on the wall.
Then we looked at the shadow that two identical combs form when one comb is moved over the top of the other.
We noticed that there were new wavy shadows that weren’t there when we looked at the combs separately. These shadows are a ‘moiré pattern.’
(Note to grown-ups: A moiré pattern appears when two identical patterns overlap. If the two patterns are on semi-transparent materials and are slightly offset, light and dark areas are created, forming a new pattern.) We thought the moving patterns were pretty interesting.
Next, we did a similar experiment with flexible window screen. When we moved one piece of the screen over another, we could see moiré patterns:
Everyone got a piece of screen. We folded the screen over on itself and moved it around to make our own moiré patterns:
Then we looked at the shadow of two transparencies covered with identical thin stripes – separately and overlapping –
and other overlapping (identical) patterns as well.
We also looked at a photo of a bridge over a highway (note the section where the fences appear to overlap) and pictures of my dining room curtains (note the patterns where the curtains overlap).
What happens if you move a striped transparency over a picture made out of striped areas?
We tried it. When we moved the transparency over the donut shape, it appeared to spin like a window fan. The wheels of the car looked like they were turning too. These ‘moving’ pictures are called ‘kinegrams.’
Once we had figured out all of that, we looked at the book, Gallop! A Scanimation Picture Book by Rufus Butler SEDER. Which is the reason that we are doing this lesson this week.. :)
Each page has a picture that appears to move and change as you open it up. The author calls these pictures ‘scanimations.’ How do they work?
To understand the ‘scanimation’ process, we reviewed ‘lenticular images.’ We learned about them in class a few weeks ago.
The pictures in Gallop! are made from a combination of kinegrams and lenticular images. A series of pictures have been cut into vertical slices and the slices alternate across a page:
Two edges of a vertically-striped transparency are attached to the left-hand page, while the remainder of it rests on top of the lenticular images on the right side.
The transparency masks all but one of the image sets at any given time. When the left-hand page is opened up, it pulls the striped transparency to the left, revealing the different lenticular images in sequence. If the transparency is moved quickly, the brain retains each picture and blurs it together with the next image. This creates the illusion of motion. Put them all together, and you’ve got a galloping horse.
We took a jumping-jack break – because sometimes you need one
and becausethat’s what the person in this kinegram is doing:
After all that, we got a chance to explore moiré patterns and kinegrams for ourselves.
Keep an eye out for moiré patterns – you never know where they’ll turn up!
See you next week,
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It’s been ages since we’ve had Science together, but I’m happy to say that I’m feeling much better now and it is wonderful to see everyone again. I missed you all very much!
This week, in honor of the letter ‘O,’ we learned about opposable thumbs.
First, we looked at a cat’s paw.
Cats have retractable claws. We turned our hands into paws with claws and tried retracting them.
Then we looked at a bear’s paw
and contrasted it with the cat’s.
We learned that another name for fingers and toes is ‘digits.’ Cats have four digits on each foot. Bears have five.
We alsolooked at a person’s hand and compared it with the paws. We have five digits on each hand and foot.
It’s good to have an extra hand if you want to pat yourself on the head!
Next, we created a cat’s paw with child-sized digits. Cats have four digits. They are all next to each other. The claws are usually retracted.
Bears have five digits. They are also all next to each other. The claws are not retracted.
People have five digits, but one of them (the thumb) isn’t lined up with the others. It is separate from the rest.
In fact,it is opposite the others. That’s why the thumb can give the fingers high-fives!
(Bear’s digits can’t really do that without moving – but they can still try!)
That’s also why we can easily touch our thumb to each one of our fingers.
Because the thumb is opposite the fingers, it is called an ‘opposable’ thumb.
Some animalshave opposable digits. Here are some monkeys with opposable thumbs and big toes:
Gorillas have opposable thumbs and big toes, as do orangutans, and chimpanzees.
Note that gorillas, orangutans and chimpanzees are apes, not monkeys. Monkeys have tails. Apes do not.
When Curious George gets in trouble and starts running away and people are chasing him and yelling, "Stop that monkey! Stop that monkey!" he never stops. George does not have a tail. He’s an ape, not a monkey. Maybe that’s why he keeps on running.
Koalas have opposable big toes on their hind feet and TWO opposable thumbs on each front foot. That’s six opposable digits!
The best way to learn why opposable thumbs are important, is to not be able to use them for a while. We prepared to do several tasks without using our thumbs by putting Super-Scientific-Thumb-Immobilizers on our hands.
Then we tried putting snap-cubes together and writing our names with crayons — no thumbs allowed.
We took off the thumb-immobilizers, took the cubes apart and used the crayons some more. We were all extremely relieved when we were allowed to use our thumbs again!!
Now we know one reason that cats don’t color with crayons.
See you next week,