I downloaded a free crochet pattern from Craftsy called the Little Sister Hat. It's apparently also available on Ravelry and other assorted sites. I used a thicker gauge of yarn and so the hat is a little bigger than the toddler pattern that I followed, but that is okay as the nerdlet has a huge head and there is no way that the toddler pattern would have fit her head. Really, I may not have followed the pattern quite right because I learned to crochet from my grandmother who mostly spoke Spanish and none of the words that she knew in English or that I know in Spanish are words for crocheting.
Anyway, I'm pretty pleased with the finished hat. The nerdlet said she will wear it and Darth Monkey says she will, too. The bear cub still doesn't say much, but she kept picking it up and taking it when it was being made.
It's supposed to be cold tomorrow so it should get some immediate use.