Surface Tension Kiwi Crate

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Travis was delighted with his latest from Kiwi Crate, a kit all about surface tension with truly delightful projects. It turns out that surface tension, the property of water molecules to want to stick to themselves, makes for both science and laughs. Here’s why!

The first experiment was to Build a Blob. Simply squirt three drops of each provided liquid watercolor onto a sheet of wax paper.

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Now use the mixing stick to pull them towards each other. The little beads are adorable skittering across the wax paper and then – slurp! They merge. This was entertaining for grown-up and kid alike to watch each time our blob grew bigger, and it had Travis in fits of laughter. When all 9 drops have merged, suck it up with the tip of a paper towel.

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Needless to say, Travis needed to repeat until the liquid watercolors were gone, including inventive games of evil empire blobs that were sucking up enemy planets.

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The second experiment was equally a delight, this time a Water Maze. Attach the felt maze outline between a cardboard base and a plastic cover with a brad. Then we filled the provided bottle with water and used the eye dropper to squeeze one little drop through the hole in the cover.

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Tilt – carefully! – and the little blob slides along (resisting the material of the base) until it reaches the center. But if we ran into a felt wall…Oh no! The felt slurps it up. This was also an absolute delight, and Travis got so silly with it. We tested big blobs and small blobs, pretended they were running away from the enemy, and more. Could they reach the center before disaster struck?

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The third project was Sticky Yarn, and had definite ‘wow’ factor. Using two sticky foam donuts, Travis attached the ends of a provided strand of yarn between a bowl and a plastic cup.

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Thoroughly saturate the yarn, then fill the cup with a little water and begin pouring toward the bowl, making sure the yarn is taut. The water “walks” along the yarn, preferring to stick to itself.

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Travis quickly learned that if the yarn wasn’t taut or if he poured too quickly, the water would spill down. Slow and steady won the race, and it was so fun to watch!

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Finally, it was time to make a Water Strider, a lesson about real-life creatures like this insect that manage to not break surface tension. First we experimented with the provided wires using the provided molds to bend them into waves…

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…or even stars!

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He practiced lowering these into the bowl of water with the provided wooden dipper so they rest on the water and don’t sink.

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Making the little “water strider” required very deft finger work, pinching three wires between two tiny bits of sticky foam. Travis crimped the legs with the wooden presses and then we lowered it down into the water bowl with the dipper.

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The bug walked on water all right! Travis tested out pressing on it with a finger to make sure we were really seeing surface tension at play, and at that point the bug sinks.

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There were a couple quick experiments in his Explore magazine for further fun. First we tried The Unspillable Bottle, an old activity that failed for us in the past, but today we got it right! Place mesh netting from an onion bag over the top of an empty water bottle and secure with a rubber band.

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Now fill the bottle with water. Place an index card over the top and flip the bottle over. Slowly remove the index card… and the bottle won’t leak!

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Travis loved the Runaway Pepper experiment the followed. Simply crank your pepper mill a few times over a bowl of water, then add one drop of dish soap in the middle.

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The pepper runs away! We leave you with this clip of it in action:


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