You are completely right about not wanting to use an iron. It would be a high risk of melting the polyester. Depending on where the tear is, you could sew a colorful patch large enough to cover the tear. Go to the crafts section at your Walmart, KMart, Target, or a local fabric or crafting store and let her pick out, one that she likes. If she likes several different designs on the patches, let her get a few different ones and arrange them however she likes them on that (or both) arms of the jacket. Before you cover the hole with the patch, you should use nail polish to seal the edges of the tear to prevent fraying when you wash the jacket. This gives her a chance to express herself, and you a chance to do a project with her. If she opts to do patches on both arms, you could sew them on one arm while she is sewing on the other. By the way, some patches come with sticky stuff on the back to hold them in place while you are sewing them. If the one(s) she picks out don't have it, you can put a small amount of Elmer's glue on the entire back, to the edges of the patch, and let it dry for an hour before sewing. Any glue that might show from under the patch will wash out. Have fun, and let her creative flag fly.