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Thursday, 17 March 2016

Green Jars

Green Jars

This simple experiment kept students occupied for over an hour. I simply had resources available and left them to it. Those who were still in doubt as to what to do simply looked at what others were doing and discussed what order to do things, checking to see if they were doing it correctly. I had the simple job of walking around taking videos and photos with my constant questions of 'why is that happening?', 'what do you think is causing it?', and 'how could you be sure?'

That got me wondering if it was because they had to follow the instructions and work it out for themselves and not having me explain the procedure to them. I'm definitely going to try other experiments this way to see if I can get the same results.

Students were really keen to try all the different sized candles with a variety of jars. They discovered that the smaller the candle and the larger the jar then the longer it took for the candle to extinguish and the more liquid was vacuumed up into the jar. But the reason 'why' this was happening provided many diverse theories.

The smoke in the jar puts out the candle

The smaller the candle the faster the liquid will be drawn in

A small candle means there is more space to fill

The amount of liquid drawn in depends on the size of the flame

The candle is sucking the oxygen up from the water

Likening the vacuum created to what occurs in space

The burnt oxygen has created empty space that needs to be filled

When we came back together as a class they filled the whiteboard with their theories and we were able to piece together all the relevant ideas to explain what had happened and why. A couple took notes of the explanation but the majority drew pictures with labels to demonstrate their understanding. 

I think we need to follow this up with some experiments on how and why hot air expands ...

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