When An Experiment Fails
At the end of STEM Class a couple weeks ago, I attempted a little chemistry demonstration – just for fun. I’d originally read about the pumpkin demo here, Rainbow Fire, and I did the experiment as described but as the kids can attest, it didn’t work. On the drive home, my kiddos hypothesized that the fact that I waited a little while for everyone to get settled may have caused the hand sanitizer to evaporate. Upon further investigation, however, perhaps I was missing a key chemical. Another site I found, Green Fire, suggested the use of Heet (methanol). A las, I will have to try again. If any of you give this a try, please let me know what you discover. 🙂
The fact that it didn’t work out though is perfect science (though very embarrassing when done as a class demonstration). When an experiment doesn’t go as planned, however hard to admit, it is actually great. It gives you the chance to go back and really figure it out. There is always an answer for why it didn’t work. You often learn more when it doesn’t go as planned.
Later that afternoon, Buddy was working on a aeronautics project (he’s trying to make an airplane with cardboard, rubber bands, and plastic propellers). When his design doesn’t work out, he gets very frustrated and laments, “I wasted so much time on this! I wasted all this glue!” (or tape, or whatever materials he used). It is difficult to console him but with my own failure earlier that morning, I had an example with which to show it happens to all of us.
Recently, another activity seemingly failed and I thought I would share our process of discovery with you …
Signs of Fall
One of the extension activities I had suggested to my STEM students when we were covering plants was a chromatography activity to investigate the pigments in leaves, Signs of Fall (scroll down for the activity “Invisible Changes”). Another link, with the same title, Signs of Fall, provides a PDF download for a student page with guiding observation questions.
My daughter and I worked together to set up the investigation just as it was described. She was even careful to measure an exact amount of isopropyl alcohol into each jar. We then placed a strip of coffee filter into each jar, taping it into place to secure it and then capping each jar with a small piece of aluminum foil. We left it over night but there was not a single strip with any color pigment. We thereby walked away, shrugging our shoulders. Another failed experiment. This was getting frustrating.
I couldn’t let this one go, however. We must have overlooked something. I thereby left it set up on the kitchen counter for another day or two while we contemplated and brainstormed what we might have done wrong. When we happened to peak into the jars a couple days later, we surmised that perhaps we had put the coffee strips into the jars too soon – before the heat of the water bath had had time to activate the pigments because the liquid in the jars was now clearly colored when before it had remained clear.
We thereby pulled off the aluminum foil, discarded our first strips and inserted new ones. We checked the progress of our test a few hours later …
If chromatography is something you’d like to investigate further, you might also consider this activity, Rainbow Candies: A Candy Chromatography Experiment for Kids. It is a great way to use up some of that leftover Halloween candy that may be laying about.
An expanded version of this lesson is available in the Science Logic curriculum
Life Logic: Plenty O’Plants.