While doing tapestry type weavings with 4th grade, I have students use five colors within their "color story". After adding their five colors, they are allowed to add a "specialty string" into the mix. They are allowed to use it 3x within their weaving. I tell them if you use it more...it isn't really "special".
What is specialty string? I have a pretty big variety that I've obtained over the years. I found some of it at Dollar Tree & Big Lots for a very good price. I found some of it in the clearance section at craft stores. I Keep my eyes open for things that are fun/different, and that I think my students could successfully weave. Let me give you all a tip...DO NOT GET POM POM YARN!!!!! Imagine a bunch of little pom-poms going through the warp strings!! UGH! Trust me...it is a headache and totally not worth it. Here is a look at the top of my specialty string box, and some weaving examples from years past (we aren't to that point yet this year...just started them!).