After studying my daughter's pinterest page, I went looking for patterns that fit with her fashion style. One of my purchases was Megan Nielsen's Tania Culottes. I bought a few lengths of rayon fabrics, and we used the cheapest one to test out the pattern.
She sewed these herself (following the pattern directions, because she shoes not like to take instruction from me. I have not read them, but I am guessing the instructions must be good, as she is a beginner sewer. She did let me show her my tricks for putting in an invisible zipper).
She is an average sized 13 year old. She cut the XS. I think she took about 5 cm off the hem, and I showed her how to do a rolled hem on the overlocker, rather than try to hem all the way round that full skirt. She was disappointed that the waistband was not closer fitting on her, but I was worried about the rate at which is growing, so rather than let her take it in, I added a length of elastic to a section of the back waistband to draw it in a bit.
For the top, I took a raglan shirt pattern (Jalie 3667), used just the front and back pieces, and cut them up and spread to add flare. I then sewed a quick and dirty neck binding that ties at the shoulders.
The hem of the top hangs unevenly, because of the bias sections and the loose weave of the cheap fabric, but she is happy enough with it. I'd like it to be longer, but she likes cropped tops at the moment.
The outfit is a win, and I think she will make up the culottes again in some better fabric. It was the right pattern to step up her skills a step. I don't love the top pattern...too short and too much flare at the front...but it was just a quick hack and I threw it away afterwards.