It’s been great spending a few days at Saint Teresa’s College of Education (TERESCO) to add a handful of low-cost experiments to their resource centre, though at times I feel like butter being spread too thin. My time in Ghana always feels too short for the work I want to accomplish, but with the quarantine requirements upon return to France, this time around I’m only here for ten days, which makes for quite a rush. Rushing and aiming for efficient use of time seem incompatible with African culture, but nevertheless, we managed to produce a number of teaching materials which I hope will go to good use.
More than ever, with the current set of experiments, I’ve been inspired by and reminded of friends from around the world who have shown me some of their favourite experiments. It’s been really cool messaging with some of them for advice and troubleshooting, and a lot of fun getting to say hi to old friends and reach out to some of the best science educators in the world. I dedicate this blog post to them, and hope they keep sharing their love of science with others, just as I am sharing it forwards
With the hope and believe that a few ideas of experiments might be of interest to those reading this, here are details on how to repeat some of the ones I’ve been sharing down here. If you want to see more ideas, please check out last year’s blog as well: tinyurl.com/Ghana2020-blog.
Forever Rainbow (learned from Anja Kranjc Horvat, CERN, awesome science show creator)
Materials: clear nail polish, the basin of water
optional – acetate transparencies, paper, cardboard
Method: Drop one drop of clear nail polish into a basin of water.
The drop will spread out quickly to form a thin film, which can display a rainbow interference pattern, depending on lighting conditions. The fast-spreading results from a combination of hydrophobic repulsion and surface tension.
The film will dry quickly, and with care can be transferred onto acetate transparency or a sheet of paper/cardboard for further observation and measurement.
Further Ponderings: If you’re unfamiliar with the science behind this rainbow pattern, look up “thin-film interference”, it’s pretty cool. It was suggested by Mr T that the thin film should be made of a single layer of molecules and could be used to estimate the size of the molecules of nail polish. This sounds reasonable to me, and I’ll think it over and discuss with him upon return to Paris, as it’s beyond the level I’m working on in Ghana at the moment. If you want some background on how this might be done, check out Matt Parker and Steve Mould’s ridiculous calculation of Pi using a similar method: https://www.youtube.com/watch?v=lmgCgzjlWO4
Marisa’s Smog Demo (learned from Marisa Prolongo, Malaga, Scientix Ambassador who introduced me to Scientix)
Materials: plastic bottle, scrap paper, matches/lighter
Method: Poke a hole in the bottle, roll up paper (roughly ½ A4 sheet), place paper roll in the hole.
Light the paper on fire. If flames are too vigorous, blow out, to attain a smouldering state.
Heavy smoke should flow down the roll of paper and mix with water vapour to form smog, which fills the bottle from the bottom up.
Further Ponderings: This experiment can be used to demonstrate how smog accumulates in cities and low-lying areas.
We considered trying to trap some of the smoke to attempt to observe Brownian motion under the cards cope but didn’t yet innovate a way to do this. It seems relatively impractical, but suggestions and advice are always welcome.
Marinko’s Scattering Experiment (learned from Marinko Petkovic, Novi Sad, Serbia. Nicknamed “Mr. Science”, Marinko is one of the most inspirational teachers I know. He has introduced me to countless amazing teachers across Serbia and former Yugoslavia, and it is largely due to Marinko that I am always keen to return to that part of Europe. Check out Marinko’s video from the Global Teacher Prize in 2018: https://www.youtube.com/watch?v=yfcti-9OX4A)
Materials: Frame with the target, “alpha particles” to throw at the target.
I don’t honestly remember what Marinko used as a frame. I’ve used old picture frames, nailed/lashed wood together and used PVC pipes, as I did this time. The exact dimensions are up to you – this time we made a 50 x 50 cm (2500 cm2) frame mounted 1m above the ground, and included targets 25.2 cm and 8 cm in diameter, 1/5 and 1/50of the total area).
Method: Bombard target with “alpha particles”. This can be students throwing any small items (we’ve used beans, seeds, corn, etc.). Those which hit the target will bounce back, most others will pass through.
After a large number of alpha particles have been thrown, the ratio below should approach equivalency:
Calculations can be carried out to estimate the size of the target using this method which is analogous to counting alpha particles reflected to calculate the size of the nucleus.
I also made a handful of PVC equipment, inspired by the Exploratorium Teacher Institute, notably a double-downhill racer (great for demonstrating angular momentum, and graphing linear acceleration without taking measurements), a stomp rocket launcher and an octave of palm pipes. Fortunately this time I had the foresight to bring a pair of PVC shears, which both saves time and improves quality. Chris was quite impressed with both the high speed and low cost of construction and seems inspired to build more things himself.
Many of the materials I put together should be demonstrated to make sense of and for ideas how to implement in the classroom. Fortunately, we were able to demonstrate a few for the three large classes of “sandwich students” (young teachers back for top-up training), but this was near the beginning of our time, and we’ve made many more since then. I would have preferred to take the time to lead these teachers through the creation of their own resources, so they’d gain experience making their own lab materials, but was told that priority should be given to their exams. I see this as yet another example of how assessment is the worst enemy of education.
Marking was also the reason why only one of the teachers at TERESCO was present – the head of science department. He showed interest in seeing some of our materials, but did not express any interest in making or contributing any of his own. Halfway through our three days there, he too left town for marking, and I was particularly disappointed that nobody at TERESCO showed interest in seeing or trying out what we had made by the end of our three days.
I plan to write up a set of instructions and make a few videos of how to use the homemade equipment, in hopes that it might help them get some use out of it, though I’m unsure whether they’ll even bother printing them out. The resource centre has a large printer, which a sticker tells me was donated by USA, but when I asked to print a couple of pages, I was informed that they do not have a cable to connect it to the computer. At least if I make write-ups, I can share them widely until they eventually find someone who might have the initiative to use them.