(in Harry Potter Gryffindor 'Apprenti Sorcier', see yarn description below)
These are on my 8 year old, who is petite and slender, but have enough ribbing stretch in them to accommodate most kids age 3 years to 8 years or more. They are easily adapted by adding in two to four stitches on the cast on edge to fit kids with larger hands and arms.
Needles: size US 2, 47" circular
Skills: magic loop, two at a time, long-tail CO, knit, purl, peasant thumb
(picture instructions below for getting started if you haven't knit two at a time on magic loop before)
I knit these two at a time on magic loop. If you prefer, you can work them one at a time on DPNs or on a circular. Just cast on like you normally would instead of following the cast on I'm giving.
CO 48 sts and pull the end loop of the circular needle out so there are 24 sts on each side.
Push the sts back up to the needle tips and exchange the end st from each needle to close the circle. Then, pull back down so you can cast on for second mitt.
With a second ball of yarn, CO 24 sts (half of your total sts for one mitt) onto one needle for your second mitt.
Now, use your other needle to transfer these sts purlwise to your other needle.
This will put your working end where it needs to be to cast onto the other needle and close your circle by exchanging end sts like before.
Holding the working end of the yarn, ready to cast on the remaining 24 sts onto the other needle.
Two sts cast onto second needle using long tail cast on.
Both mitts cast on, circles closed by exchanging sts, with separate balls of yarn for each mitt. Ready to knit :)
Now that we are cast on and ready to go, when you are working with two at a time, you will knit along the first side of one mitt, then you will knit along one side and the other side of the second mitt, then you can finish up the last side of the first mitt and you will have completed one full round on each mitt at this point. I find it helpful to add a little stitch marker to the first mitt (or sock if I'm knitting socks) so that I always remember when I complete a full round on both. I usually just attach an clasp-type marker to the first row of knitting after I've completed a few full rounds and leave it there until I'm done.
*K2, P2* repeat in asterisks for each round, until you have knit 3" or 4" for the cuff and hand portion of the mitt. My example is knit in 4" length.
Using a waste yarn of contrasting color (important it's contrasting so you can find it easily), knit 7 sts onto waste yarn, then tuck ends inside work and pick up regular working yarn, leaving a comfortable float where you knit with the waste yarn.
Continuing knitting in pattern of K2, P2 for another 1" to 1.5" (example is knit in about 1") to complete the mitt. Use a stretchy bind off like Elizabeth Zimmermann's Sewn Bind Off
note: I usually bind off one side and then use the needle I just finished on to transfer sts onto so I can continue around in my bind off. You will only need to do this for the first mitt, as when you get to the second it's the only one left on the needles.
Carefully remove your waste yarn and put the live sts onto your needles. Knit around first 7 sts, pick up 2 sts on side, continue onto other needle, knitting other 7 sts and pick up two more sts on other side of thumb.
Continue in pattern now of K2, P2 for about 5 rnds and bind off using EZ's bind off like described above for mitt bind off.
Do the same for second mitt. Any questions or corrections, please comment or email me so I can update. Thanks!