Tuesday, January 24, 2012

Rock Candy wrap up

Have you been worried about the eight jars of sugar sludge hanging out in my classroom?

First off, there are only seven. In a move of typical clutziness, I knocked one over this morning. Sticky sugar clean up on aisle five!

The very happy news is that although my test run at home did not produce the desired results, the remaining batches at school are all slowly creating crystals of sugar. Very slowly. Like, I am wondering if I'll be able to clean it up before February vacation.

Today we finished the experiment part of the project. Although the recipe part isn't finished, we had collected enough data to bring some closure to the experiment. So we brought out the jars, made a final round of observations, and then looked back at the question: What will happen to a sugar solution if we heat the solution and leave it sitting for several days? The class hypothesis was that some of the water would evaporate and would leave behind sugar crystals we could see. This was, indeed, what happened. However we talked about how even when scientists disprove a hypothesis, they learn something new about the world and how it works.

As we talked through what had happened and why it had happened, lots of good questions came up. I captured these on a chart paper list started last week. Some of these questions may be fodder for student-designed experiments later in this unit. One student wondered if the crystals would grow better on string instead of the wooden stirrers we are using. Another wondered if room temperatures could affect crystal growth. (This after I showed them my sludge from home and they questions how hot/cold it is at my house, trying to reason out what had happened.) I am writing this from home but at some point I will post a photo of this chart paper list; I am always excited by the sorts of questions students articulate as a science unit of study is under way.

One point that came up in our observations is that it was hard to be sure that the water had actually evaporated. Duh! We should have either measured the height of water in the glass jars each day or better yet set up one container in a graduated cylinder or some other type of measuring cup so we could collect numerical data. It's a learning experience, right? Instead, we talked about the importance of a well-designed experiment. Hopefully I can model this better moving forward and students can learn from what I do as much as from what I overlook.

While our "recipes" in the next few weeks aren't as elaborate as they were for the US Geography unit, they will be more frequent. We will be straining applesauce tomorrow, freezing juice pops on Thursday and making salad dressing on Friday. Check back soon!

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