Posts tagged: vision

Make a Salad Spinner Zoetrope

By , October 16, 2009 5:03 pm


The theme for this week’s Unplugged Project was wheel.  I searched around for ideas and came up with this one which sounded really interesting:  a zoetrope!

What is a zoetrope you ask?  (I didn’t know what it was either.)  A zoetrope works on the same principle as a flipbook, one of those little books where you flip the pages and it looks like an image is moving, but it uses a rotating cylinder to produce the illusion of movement.

I like this definition from Wikipedia:  “A zoetrope is a device that produces an illusion of action from a rapid succession of static pictures.”  The word zoetrope comes from the Greek zoe (life) and trope (turn), so it is really a “wheel of life,” perfect for our theme!

I found instructions for making a zoetrope many different ways:  using a round camembert cheese box, a PVC pipe, a straw and a printout, a paper plate, and ice cream containers.  We originally made up our own version out of black poster board, an old CD, a small lazy susan, and lots of tape.  It was OK, but a bit wobbly.

Then I found a totally ingenious person who made one out of a salad spinner!  Why didn’t I think of that?  We absolutely had to try it and the result was AWESOME!  It is an easy project that produces a maximum “wow factor.”  Try it, here’s how:

Use electrical tape to tape off the slits on the salad spinner basket leaving every third slit open. We used 3/4″ electrical tape and that just happened to be exactly the right size for the job.

For images, the salad spinner genius used cutouts of the phases of the moon from a calendar.  Very clever but I decided to draw my own pictures.

On a piece of white paper I marked off a series of 3/4″ x 3/4″ squares.

Then, using a black Sharpie, I drew a face with a changing mouth and waving hair, making each image slightly different than the previous one.

The tedious part was cutting out all 26 images and taping them in sequence to the blocked off areas of the inside of the salad spinner.

Finally, using a clump of rolled up tape, stick your zoetrope onto the overturned lid of the salad spinner, centering it as best you can. The zoetrope will be sitting on the rotating disk, and the salad spinner handle will be underneath.

Now for the fun: spin and look through the slots to see the “movie!” The view is best if you shine a bright light into the bowl of the zoetrope.

Hopefully you’ll see from this little 10 second video that we made, how cool this project really was!

Let’s not forget THE SCIENCE:

So how do flipbooks, zoetropes, thaumatropes (a rotating card with a different picture on each side, the pictures appear to combine when card is spun), cartoons, and old time film movies actually work?  Many people still believe in the “persistence of vision” theory, in which it is thought that an image remains in the eye for a certain time after the image source is actually gone (ie. the optic nerve is the cause).  Apparently that theory is no longer in favor these days.  A more popular theory at the moment involves something called Beta movement where the brain itself apparently combines rapidly flashing images thus forming a perception of movement (ie. the brain is the cause).  It seems that no one really understands any of this completely.


You can visit a real zoetrope at the following museums:

V&A Museum of Childhood, London, UK

The Ghibli Museum, Tokyo, Japan

Great Lakes Science Center, Cleveland, Ohio, USA

Headwaters Science Center, Bemidji, MN, USA

Have fun!

(Be sure to visit the links to other people’s wheel Unplugged Projects on last Monday’s Weekly Unplugged Project post.)

"EYE" Have Been Away

By , July 12, 2007 7:54 pm

I have been very silent for the past couple of days, but we were away in Albuquerque for our annual visit to the pediatric ophthalmologist. During the long drive home, I was pondering my next post. Since most of my readers probably have children, I thought that children’s eyes might be a good subject for a post. My experience with my oldest daughter has taught me a lot that I did not know before…and that you may not know either.

When my oldest daughter (now 6) was 1, we took her to a pediatric ophthalmologist to have a congenitally blocked tear-duct surgically opened. During our initial visit, the doctor did a thorough eye exam, including a vision test. Many people (including me before this event) do not realize that it is possible to test the vision of an infant.

During the exam he discovered that not only was my daughter far-sighted, but her two eyes had a huge difference in the level of vision. This latter issue, as I learned, is a real problem that if left untreated, can actually cause blindness in the eye with the worse vision.

During childhood, if there is a big difference in the quality of vision between the two eyes, the brain will use only the good eye and will ignore information from the bad, or “lazy” one. This is known as amblyopia, or lazy-eye. Many people do not realize that a child does not have to exhibit an actual misalignment of the eyes in order to have “lazy eye.” My daughter had absolutely no physically obvious manifestation of any vision problem.

Common treatment consists of patching the good eye to force the “lazy” eye to be used, or prescribing glasses for the same purpose. My daughter is being treated with glasses, which she has had since age 1.

Apparently, 2 to 3 out of every 100 children are affected by this condition. What is scary to me is that routine, very early vision testing is still fairly unusual.

The earlier treatment occurs, the better. My understanding has always been that treatment must occur before age 7 or 8, otherwise it is too late. However, a study by the National Eye Institute (NEI) found that children up to age 17 can still derive some degree of benefit from treatment, although dramatic improvement seems to be less likely as age increases.

Of course, although I have had many “careers” in my lifetime, I am not a doctor! I am simply trying to pass along what I learned from this experience with my daughter – get your children’s eyes tested at as early an age as possible, even if everything seems fine!

Having learned about this issue with my oldest, I have had my two subsequent children tested early. My son first went to the pediatric ophthalmologist at age 1 (and was retested at 3, and again today at 5 to rule out any possible vision changes), and my second daughter had her first visit today (at age 18 months). Fortunately, the two younger children, so far, seem to have absolutely uniform, normal vision.

The little ones hate being tested, especially the eye drop part, but the whole process is quick and painless. The chance of detecting and preventing a potentially severe and irreversible vision problem seems well worth suffering through a few moments of uncooperative behavior! I also recommend seeing a pediatric ophthalmologist if possible, since they are used to dealing with unwilling patients and are perhaps more familiar with the vision issues of childhood.

Resources and information:

NEI Amblyopia Resource Guide

30 second video animation of Amblyopia and treatment by patching

Find a Pediatric Ophthalmologist

The American Association of Pediatric Ophthalmology and Strabismus

Prevent Blindness America

Taking Care of Your Child’s Sight

Thanks to the National Eye Institute, National Institutes of Health for the anatomical diagram of the eye.

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