In this 5 minute video, Charlotte has done a great job communicating basic geology facts, with drawings, photos and a simple but effective narration. Kudos to Charlotte for her efforts! And... you may want to consider using it when you are exploring this topic with your own Juniors! 

Pegmatite is a great example of an intrusive (also called plutonic) igneous rock because it is formed as magma cools deep underground. By cooling very slowly the crystals of quartz, feldspar and mica can form really big crystals. Pegmatite makes it easy to see how these common "rock-forming minerals" can combine to make a rock. Every leader ought to have an example like this for teaching.