Actually, a second sock toe is tucked inside the outer one and there are twice as many stitches on her needles as she would have if she was just knitting one sock. The stitches for one sock are interleaved with the stitches for the other sock. She knits with one yarn in either hand, knitting a stitch for one sock with its yarn, then knitting the next stitch--a stitch for the other sock--with the other yarn.
No matter your age, or how many socks you've knit, it was delightful, even magical, to see the inside sock pulled out!
See more photos from the workshop and post photos of what you're doing with your blanks on the guild's Ravelry page.