What is an igneous rock? That was the question that was asked .
I explained that an igneous rock was essentially a volcanic rock, either having cooled under water, or in the air.
One mixture we put in a tray in the freezer (water), and left for fifteen minutes – and it came out flat and shiny, like obsidian rock, and those volcanic rocks that are cooled under water.
The other mixture we left to cool in the air, to observe the following week. As expected, in hardened in a bumpy ‘rocky’ fashion, with air holes, not unlike basalt, a volcanic rock cooled in the air, which we had also observed (above).