Yesterday, I wrote about a Woodland Park tradition. Here's another one.
It's a variation on the classic sink or float experiment. We start with a jar of water, then test various objects to see if they are more or less dense than the water -- a wine cork, pink eraser, paper clip, apple slice, grape, piece of candle. After taking a moment to share our thoughts on this and other things that may or may not sink or float, we dump the whole thing out, fill the jar halfway with water, then begin again. This time, however, we start by adding some vegetable oil to see that it starts by sinking into the water (carried by its momentum) then forms into blobs and rises to the surface, ultimately settling into a nice, thick slab of one liquid floating atop another. Someone will almost always suggest we put on the lid and shake the jar, which we do, then sit watching as the liquids, miraculously, re-separate.
I perform this pretty much like your traditional teacher-in-front-of-the-room classroom experiment. The kids have daily opportunities to play with water and even get their hands into vegetable oil on occasion as well, so they've had a couple years worth of free-play experiments under their belt. One thing I like about doing this sort of thing every now and then is that it gives the kids a chance to practice accommodating their friends. At each step of a process like this, there are some, sometimes most, who bounce up onto their knees, even to their feet, who can't help creeping forward, who, when left to their own devices would move inextricably closer until they're sitting on my lap, nose to the glass, all clear signs of intense interest, which is a good thing. Unfortunately, this always leads to calls of, "I can't see!" from those who want to take it in from a more leisurely distance. There is jostling for space and sight lines, even a bit of pushing.
We all scoot back, put our bottoms on the rug, and otherwise adjust our bodies to make it possible for the whole group to see what's up, looking over our shoulders in an exercise in putting our eyes into the heads of others. Then as the experiment resumes, the inexorable return movement toward me begins again, like a tide. It used to frustrate me, but now I see it as a necessary part of what we're doing: an experiment in how to make it possible for everyone to see. I've learned to perform most of the official experiment within those bubbles created just after they've backed away.
After we're convinced the oil will always float on the water, we break out a jar of molasses. Most of the kids are unfamiliar with this tar-like syrup. They each get a chance to smell it, as they did previously with the oil, and I move it around in the bottle so they can see its thickness. We then make our predictions about what level to which it will sink. Will it float on the oil? The water? Will it sink to the bottom? As it streams to the bottom of the water (I pour it over a spoon to create a slow steady flow), many of the kids are convinced it will "bounce back" like the oil did, but soon we're all convinced it's the most dense liquid of the three. We then return to our solid objects and test them one at a time, predicting, then witnessing at which level they will settle. I choose this particular collection of objects because I've learned that there are some that will float on oil, some on water, some on the molasses, and some that will go all the way to the bottom.
We finish by putting the lid on the jar and setting it on a shelf at eye-level, where we leave it, promising to make new observations in the coming days. Over the course of the following days, we notice some of the objects, having absorbed one liquid or another, change their density and sink to lower levels as time goes on. The molasses eventually dissolves into the water. After a week or so of intense observation, we then tend to forget about our jar for a long time.
We started this experiment in September. Recently, there's been renewed interest in the jar on the shelf. Now I've learned from experience that one of the most significant, easily detectable changes is in terms of oder. A few years back, Luca's mom was tasked with the year-end job of cleaning out the jar to prepare it for the following school year. She removed the lid, began to retch, then just threw the whole thing in the trash, electing to instead buy us a whole new jar. It's a pretty vile smell.
Yesterday, we decided we were going to smell for ourselves. A few took my word for it, wanting nothing to do with it (a group that included most of the adults), but most chose to whiff for themselves. As the children who were going to brave a sniff moved to one side of the rug, while others took up spots on the far side, I told them
the story of the stink dough (click through if you dare), finishing with this admonishment: "I'm going to be taking the lid off this jar. The stuff inside is very stinky. If I spill it, it's going onto our rug or onto
you. I don't know what will happen if it gets on you, but if it gets on the rug, our whole school will stink for a loooong time. Stink dough was bad enough: I don't want to come to a stink school." After their laughter died down, I earnestly explained how important it is that they don't try to smell it with their hands, that they remain calm and still as I pass it under their noses, that there be no bumping, pushing, or fighting for space lest they cause me to dump the contents on them or the rug. I painted the prospects as a potential tragedy because, indeed, it would be, believe me. The stuff, as I said, is vile: like the most intense stinky cheese you can imagine . . . then assume it's a little worse.
As I waved it under their noses, one at a time, no one popped onto his knees, no one jostled. Everyone had plenty of room and perfect sight lines. Indeed, they remained as still as statues, even as they retched and squealed and pinched their noses.
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