One of the challenges of teaching in a developing country is that you can't just walk down the street to the local School Supply store and pick up the equipment you need for a science experiment. Well, maybe in some developing countries you can, but definitely not here in Cambodia. So that means you have to get a little creative, visit a few (or sometimes many) different stores, and try out some more unusual options. It also means you have to think ahead a bit.
This coming week I've got an experiment to complete that is part of our International Primary Curriculum (IPC) unit called "Investigators". We've almost finished our Investigator Training, and we are currently investigating an accident scene involving a victim with blistered lips! This particular experiment requires students to determine the heat insulation properties of various different types of cups. Just collecting the suggested types of cups was the first challenge.
The experiment called for four types of cup: plastic, paper, polystyrene, and metal. Now plastic is easy, and so is paper. Metal reminded me of the metal cups we used in the dining room when I was at boarding school back in 1980. Then I saw some photos of those multi-coloured aluminium picnic cups that most families seemed to have when I was growing up. A photo on Google reminded me of my old enamel camping mugs, great for keeping a cup of herb tea hot on a cold night! My colleague did some hunting around town for metal cups with little success, so I did some hunting of my own. I eventually found some small stainless steel mugs like this one.
So now I've got all my cups lined up, the next challenge is how to measure insulative property. The suggested procedure is to pour hot water into each of the cups and measure the temperature over time, so see which cup keeps the water hot for the longest time. That would require a laboratory thermometer, of which we have none. My colleague thought he had solved the problem when he bought some clinical thermometers, and some clever person suggested putting each cup into cool water, and monitoring the temperature of that cooler water, to see how much it heated up. He tried it this week, and it sort of worked, but the narrow temperature range was something of a problem. I am also hesitant to use them as they look very suspiciously like they are a mercury thermometer, and I don't want the responsibility of mercury in my classroom.
After having hearing his experience, I thought about using standard weather thermometers. While their range isn't a wide as a laboratory thermometer, it does go from -40°C to +50°C, and the ones that I bought cost me all of $1.80 each. I just did my own mini-experiment to see if they would measure water temperature and here are the results.
We'll see how it goes next week, but I'd say that's another successful modification to a project in order to use materials I can actually get my hands on!