Thursday, February 03, 2011

Continuing To Let It Ride

About a month ago I posted here about four "accidental experiments," the first of which I described in detail in this post, and involved a flooded aquarium in which we had sprouted various seeds and included the demise of at least one poor worm.

The water had become increasingly murky and the insides of the glass covered in a green film. This experiment unceremoniously ended this week when Peter tried floating a favorite small metal car on the surface of the water, then shouted in despair, "It sunk!" Upon closer inspection, I found that the 10 gallon tank was pretty much full to the top with toys and other debris deposited there by children over the last month. A gang of us bailed out water until it was light enough to just dump, allowing us to rescue the toys. 

Our experiments with ice in the outdoor classroom ended, naturally, when the weather warmed up.

The 2-liter soda bottle green house experiment ended with the advent of our new and exciting "garden tent." These half-bottle mini weather shields seem to have done their job of keeping our sprouts alive, the onions thriving, although shockingly, something managed to get in there and nibble on the broccoli leaves. Probably slugs, which means we'll need to build a few more beer traps.

The final accidental experiment from that early January post involved the continued observations of an experiment that perhaps should long ago have been thrown out, but has now evolved into a first stop each Tuesday afternoon when the Pre-K class convenes.

We started by putting water, vinegar and baking soda into a jar with a handful of pop corn kernels, dry kidney beans, and sunflower seeds in the shell. In the beginning the seeds floated, the beans sank, and the pop corn danced from top to bottom and back again on the fizz of the carbon dioxide created by the chemical reaction of vinegar and baking soda. (The original experiment is explained in more detail at the bottom on this post.) Instead of tossing it out, however, we let it ride, leaving it on a counter for future observations (i.e., I got busy with something else and forgot about it).

As I described in the last post:

Within a few days, we noticed that the few remaining bubbles were now able to lift the beans, leading us to speculate that having spent time in the water had made the beans less dense. The sunflower seeds were still floating on the surface, which meant they were still less dense than the water. This new revelation in hand, I would have tossed the whole thing, but several of the kids wanted to see what would happen if we left it awhile longer. My private prediction was that the beans in water would eventually lead to a mushy, smelly mess, which is why I'd entered the classroom yesterday morning, after over a month of soaking, anticipating a nose full. Nothing. This told me that the lid has a pretty tight seal. But our eyes told us that something unanticipated had happened.

With no more carbon dioxide bubbles to lift them, the popcorn kernels and beans remained on the bottom of the jar, but look at the sunflower seeds. There they are, suspended like magic in the middle of the water. Now that's a pretty cool result. We're speculating that the seeds have now absorbed enough water that they are more or less the same density as the water.

It's now been another month and the sunflower seeds have joined the rest of the solid objects at the bottom of the jar. We've noticed that the liquid has become darker, leading us to speculate that "little bits of the seeds are getting in the water." I tossed out the words "dissolve" and "disintegrating" for the curious. But most interesting is what Lachlan described as "a beard" that has grown on the surface.

The kids wanted to open the jar, but I'm 100 percent certain that act will release a stench so foul that we'll need to evacuate the building . . . Well maybe not that strong, but we'll never get that genii back in the bottle and I'm pretty sure we'll then want to throw it out. I explained my theory and asked, "Do we want to go outside and open it, then throw it out or should we keep the lid on and keep the experiment going?"

Only one of them voted to throw it out, so once more we're letting it ride.

(When we do finally open it, and we will at some point, I'm going to make darn sure we're all wear surgical masks because I sure don't want anyone breathing that mold!)

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Play said...

Heh Tom, Love your experiment! That is so cool about the sunflower seeds. Heh, just want to say, my class put a pumpkin a jar once to see what would happen and when we finally opened up the jar: poof! There was quite an explosion so do be careful and make sure you point your jar in a strategic direction :)
Thanks for sharing. Tdeb:)

BSK said...

Let it ride... why not? What's the harm...

BSK said...

Sorry, did that come off snarky??? I hope not. I meant to convey that these little experiments are amazing in that they are all reward and no risk (except the potential smell). They don't eat up a ton of time, space, or materials. And they'll dazzle the kids and provide opportunities for learning, insight, curiosity, and wonderment.