For our final presentations, the university students showed the science groups the wonders of natural indicators while the mathematics groups wove palm leaves into shapes with unique angles they then analyzed.
The process for the indicator activity started with preparation of 6 common plant materials: red onions, turmeric, purple sweet potatoes, banana flower, and two kinds of decorative flowers. Each of these was reduced to a pulp with a grater and/or an improvised mortar and pestle: a cup and a wooden stick.
After that a bit of alcohol was added, the solids were strained out, and a sort of tea was made from the material. This was the indicator. Each of 6 groups prepared one of the indicators, and then introduced it into 5 different solutions with different pH: tap water, vinegar, dilute battery acid, soapy water and lime water.
The range of colors that resulted was astonishing. One by one the groups showed their colors to their colleagues, and then set them in order on a table in front.
Left to right the columns are soapy water, lime water, tap water, vinegar and battery acid. Top to bottom the indicators are banana flower, red onion, turmeric, purple sweet potato, and the two flowers. Among other things, it was fascinating how some indicators showed yellow for base, and some showed yellow for acid.
The mathematics groups concentrated hard to get the base move down for the simple weave. There are really only a couple of motions, but each time they must be done just right.
After everyone was on the right track, we got out the protractors and had them measure the angles they were making. Amazingly enough, nearly all the angles turned out to be 60 or 120 degrees.
It turns out this particular weave is in some of the most common baskets the Timorese use on a daily basis, and the angles almost all follow this same pattern. Just the idea that the baskets that Grandma makes have a load of mathematics within them can be inspiring and empowering. We certainly saw the students take a great interest.
Next week we’ll meet one last time to prepare for the expositions, during which the high school students will present to their colleagues, with the university students backing them up. It should be exciting!