purple pen caper

I would first find out which people have motives to steal the pen.  Then, I would start to figure out where everyone was when the pen went missing.  I would then start to interrogate the most likely person to take the pen.   I would also walk around the class room to see if anyone has hidden the pen anywhere near by.  I would also check Hudson's desk just to see in case she missed it when she was looking around for it. With my luck it would have been hidden and taken very carefully and secretly.  So, the pen would end up in the great trash can in the sky.