This last week was our final week of Fall Semester at Walden School, and for their final test my chemistry students planned, practiced, and presented chemistry demonstrations to their peers and to Walden’s elementary classes. Altogether five groups of students presented to the elementary school on Wednesday, Dec. 15 and the rest of the student teams presented on Friday, Dec. 17.
I’ve discussed my rationale for doing this in previous posts: that this is an excellent method for generating excitement about STEM in elementary students as they see their older siblings and high school students working with and presenting science. Certainly the younger students were very excited and attentive; they were eager to participate and asked good questions.
For me, though, the real reason for doing anything in my classes is always how it will benefit my students. Taking 3-4 days out of our curriculum to practice and present these demonstrations is hard to justify unless it has strong pedagogical advantages. The justification is this: as my students write up their demonstration scripts and outlines, as they practice talking about the science they are presenting, and as they prepare to answer questions from the audience they are thoroughly learning the chemistry behind their demonstrations. They are going beyond hands-on labs to share what they have learned, and that learning will be indelible.
The topics of the demonstrations had to related to the individual element/materials research project of one of the group members, which they are continuing to work on. Here’s what was presented:
Sofia, Karlie, and Jerry demonstrated the principles behind hand warmers by showing the rapid crystallization of sodium thiosulfate crystals that had been heated and then cooled down. They also talked about crystals in general.
Ryan and Casey, with help from Chelise, Lindsey, and Mari, demonstrated how to make gak (a polymer made out of white glue and borax powder). This is an old standby demonstration, and the kids really enjoyed it.
Genny, Rachel, Morgan, and Jared demonstrated aspects of copper chemistry. They handed around samples of copper ore (Rachel’s uncle is an engineer at Rio Tinto’s Bingham Canyon Mine in Utah) and showed a methanol version of a flame test (including copper salts). Jared demonstrated the alchemist’s dream reaction: turning copper into gold (actually brass).
Sam and Sid, with help from Josh, presented the idea of magnetic induction and discussed how modern electrical generators work. Sam actually built her own alternator and induction coil, and Sid presented on his research about the use of wind power to generate electricity. They also created a fun kinesthetic activity to show induction.
Karl, Nicona, and Tanner presented on the properties of the elements; they did a flame test as well, and demonstrated what magnesium ribbon looks like when burned and how fireworks get their colors. They also had sparklers for each of the students to try out.
In class on Friday, the other groups presented their demonstrations. Sonora, Morgan, and Dallas presented the red cabbage pH demonstration that is one of my favorites.
Courtney, Holly, and Mari showed how to untarnish silver using baking soda and aluminum foil. They even included a correctly balanced chemical equation, although we won’t be learning about those until we return in January.
Chelise, Lindsey, and Libby presented the properties of carbon dioxide gas and dry ice. They showed how regular matches go out in carbon dioxide, but that magnesium burns even brighter when placed in carbon dioxide.
Jace and Olivia talked about gunpowder, how it is made, and why it is dangerous. Jace has experience working with black powder (he has his own muzzle loader – this is Utah, after all) and he created some raw gunpowder, which he burn outside. They also demonstrated the “fire writing” demonstration of drawing on a piece of paper with a saturated solution of potassium nitrate, then touching a wooden splint to the edges of the writing to see it burn letters through the paper.
Josh and Jess presented on salt solutions and how they can be used to determine the density of objects. They showed how an egg will sink in pure water but will float in salt water.
We also videotaped as much of the presentations as we could and took quite a few photos; those students that weren’t helping present helped with the photography.
When their demonstrations were done on Wednesday and Friday, my students were excited about what they had done and the feedback they’d gotten from the younger students. They still have to learn some showmanship and presentation skills (which we’ll continue to work on), but based on what I saw and what the elementary teachers reported, the science content was excellent. They and their peers filled out evaluation forms (and I will as well) so that they can improve on their presentations for the next round in January.
It was a lot of work to prepare for this. Now my lab room is a mess and I’ll need to take a day during Christmas break to clean up and re-organize (and I think I forgot to throw out the leftover red cabbage pulp that’s in my trash can, so I’d better go clean up tomorrow). But despite the work and the lost time, I’d say these demonstrations were well worth it. As we go through the second semester, the students will present at least twice more, including a final time at a back-to-school night for their parents. We’ll polish the delivery, add more science explanations, create slide shows and videos to supplement their demonstrations, and by the end of the year these will be incredibly well done.