I admit I am overly ambitious.

This week is Dr. Seuss week (since when is this a thing?) at my children’s respective schools. I came across this adorable fabric at 40% off and a 40% off coupon at Joann’s and it called to me. I had a momentary fit of delirium when I thought it would be possible to knock out two little girls dresses in a week (not to mention two ties for my sons).

It was all going along fine until I got to the sleeves.

The pattern directions call for a closed armscye (which is apparently a fancy word for armhole).  Here are the directions:

I’ve set them in on sweatshirt sleeve before but with ribbing that stretches. For the life of me, I can’t figure this out. It seems it would be easier (and less error proof) to set the sleeve in flat and then sew up the bodice lining and sides. (I’ve not been impressed with the directions thus far). I ripped out the stitching on one side to try a flat insertion:

But kept the other side closed in case I can figure it out.

Please accomplished sewists, take pity on me. Can someone help with this problem? Photos or links would be a huge help. Thank you in advance.