These tiny beads create an amazing phenomenon- absolutely captivating in the classroom!
This is eye candy!
The Water Marbles Demonstration Kit is now available!
Made of a super absorbent polymer, these beads can soak up a surprising amount of water. Just put some in a beaker, add water, and allow them to sit. Over several hours, they’ll swell up to as much as 10 times their original size! These beads are just enormous- the largest water marbles you’ll find! 3mm dry beads expand to about 40mm in diameter, absorbing about 300 times their weight in water! They feel spongy and bounce, so students love to handle them!
These beads also present a phenomenon that will have students rubbing their eyes and thinking you’re performing magic! Since the marbles have the same refractive index as the water they are place into, they appear to vanish and become invisible! You can reach your hands into what appears to be simply a beaker of water and pull out a handful of huge water beads- as if from nowhere!
This is such a great way to launch a lesson or unit on:
- Polymers
- Density
- Osmosis, diffusion, hypotonic/hypertonic, semi-permeability (The beads can represent cells, because their membrane is semi-permeable. Add salt/sugar water and…)
- Refraction and refractive index (they become “invisible” when placed in water because the refractive indices of both the water and the beads are the same.)
- Snell’s Law
- Surface to volume ratio
Water beads are environmentally friendly since they are 100% biodegradable.
- Add food coloring to the water and you’ll have colored Water Beads!
- Water Beads can actually be dried out and reused.
Water marbles are composed of a cross-linked polymer called polyacrylamide. The many C=O bonds and NH2 groups in the polymer form strong hydrogen bonds to water molecules, and the polymer readily absorbs large amounts of water, forming a polymer gel. The water marbles will absorb roughly 200 times their weight in water. Because it is composed of almost entirely water, its index of refraction is essentially the same as water, which is why it seems to “disappear” when placed in water. Since air has a different index of refraction than water, the marble is visible when removed from the water.
