T just turned five. We'd done some minor weaving stuff together (and a bit of spinning and knitting) before, so I got him a pot holder loom made by Harrisville Designs (our local toy shop carried it). In one day, we have finished one potholder and done all the weaving on the second (we still need to finish the edges). There's two loops left over, so we clearly need to get more--in bulk. He doesn't want to weave by himself, but he clearly understands the over-under-over-under aspect and the process for finishing the edge.
Also, my Spin Off magazine arrived today, and he insisted on sitting on my lap while I browsed through to see what was in it. At one point he asked me to go back several pages so he could "look at the cute drum carder again".