This is another science experiment we initially did at my son's Halloween party. But at this point I've 'performed' it at a home party, and also while doing science at my daughter's class, and it was a hit every time. I love this experiment because it pretty much works like a magic trick while really being based on science. It is nice and easy (the only thing you might not have on hand are the jelly marbles), and it is easily adaptable to pretty much any party/holiday theme just by switching the hidden image/message. Plus the sensory aspect of this is something kids of all ages (and I mean all ages!) absolutely love!
Jelly marbles (also known as water beads) are super-absorbent polymers used extensively in the commercial horticulture industry as well as for residential gardening. They have the capacity to absorb and release up to four hundred times their weight in water. Having that said, you should be able to find them in your local nurseries, but I just find Amazon so much more time-efficient. So, this is where I got my jelly marbles. That package will last you a LONG time (two teaspoons of this stuff can swell and fill up a 1.5 quart vase), but believe it or not, there are actually quite a few uses for water beads (playing, decorating, etc.), and in any case, I can pretty much guarantee your kids will want to do this over and over again.
If you have a laminator, it might be smart to laminate your images. Otherwise, just keep in mind you probably won't be able to re-use them.
Preparation
The night before you plan to perform the experiment, place about a tbsp of the jelly marble pellets in a large bowl (#1). Add water (fill up about 3/4 of your bowl), and leave the pellets soaked for about 8 hours (#2). The next morning your marbles should be ready (#3).
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Let your kids touch and feel them because - well, just try it yourself - these beads are pretty awesome!
The Experiment
Ok, when they're done touching, feeling, and observing, it's time for the actual experiment. Take your image, and place it discreetly under your bowl. Then show 'your audience' the bowl again. They shouldn't be able to tell what the image/message is. They might be able to see some blurred colors, but that's about it.
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Now, start to add water. As the marbles start to become invisible, the image will slowly become more and more clear (see #2 above and #3 below). When the marbles are completely covered with water, they should be completely invisible, and the image will be completely clear. At that point, 'your audience' might ask if you've caused the marbles to dissappear. In which case, you can easily show them that the marbles are still there in the water - they have just become invisible!
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How Does It Work?
The jelly marbles are filled with water. Before we poured the water in, we could see the outline of the marbles in the bowl. But after we poured the water in, the jelly marbles became invisible. That is because the jelly marbles are filled with water, and therefore have the same index of refraction as water. So, when light comes through, it is not bent, and the marbles become invisible, which enables us to see through them.
Ready for More?
I hope you had fun with this, and while we're on the topic of ghosts and Halloween, make sure to check out my Boo Bubbles post where I show you how to create these amazing fog-filled bubbles that you can hold and bounce. There is also the Crystal Ball Bubble post, which shows you how to grow a bubble out of a bowl, and then of course, there is the Spooky Expanding Ghost experiment with a twist on the familiar baking soda and vinegar experiment. We had so much fun with these experiments in my son's Halloween class party, and have repeated them quite a few times since :)
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| Dry Ice Boo Bubbles | Spooky Expanding Ghost | Dry Ice Crystal Ball Bubble |
As always please share your experience. I'd love to hear of all the creative ideas you come up with in regards to making use of all these extra water beads! See you all real soon,
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