Hi, I learned to knit when I was a child but have forgotten how so I’m trying to re-teach myself using a video on the internet. I am following one that shows a long tail cast-on. I am finding that as I cast on the loose end of the yarn gets shorter. Is that right? I don’t remember having to think about how long the loose end is when you start but perhaps I was casting on with a differnt method back then. The video only shows a few ‘stitches’ (I know they aren’t called stitches, I mean ‘loops’ or ‘casts’ maybe, not up with the lingo) so I can’t see if this is happening there too. I have tried having the loose end in front and the ball of wool end in front and it doesn’t seem to make a difference. Can anyone tell me if this is normal? If so then I shall ‘cast away’. If not… back to the drawing board I guess.
Thanks in advance.
Re-teaching myself to knit
Yep, that’s the tail yarn and you’re using it around the thumb, and it’s whay you need to figure out how much you need. The other yarn gets ‘shorter’ too, but since it’s attached to the ball or skein, it’s not really noticeable… 
You might have used a knit or cable cast on which start at the short end and use up the working yarn. Or maybe you just used the backward loop CO which is the same as what you’re thumb does on the Longtail only the other yarn isn’t involved. I wouldn’t recommend that one to start a project with as they’re tricky to knit into and are very loose.
Thankyou, I will press on in that case leaving a longer tail yarn. I will have more questions before long I’m sure so thanks for the speedy response.