The finished mermaid tail blanket:
Dollar's niece loved it. They told me she'd go nuts but I wasn't anticipating how nuts she'd go. She got into it immediately and was "swimming" across the floor all evening.
Pattern: Mermaid Tail Lap Blanket for Children and Teens (rav link). I made the in-the-round version
Size: 6 to 7 years
Yarn: Caron Simply Soft, less than 6 balls, yarn held double throughout
Needles: US 11
I used acrylic yarn because it's inexpensive and can be machine washed. The materials for this project were less than $18, which makes it a nice, economical project. I encountered no knots in any of the 6 balls. I even have two entire balls leftover.
This is a pay-for pattern but I think it's well worth it. The instructions are well written, there are a variety of sizes and two construction options: in-the-round (for a sack-like result) or back-and-forth (for a blanket-like result). I did in-the-round because ain't nobody got time for back-and-forth during the holiday knitting frenzy.
After so much knitting on US 11, I went back to working on some socks on US 6 and it felt like I was holding toothpicks. I'm going to have to gradually work back down to feeling comfortable on smaller needles.