Cast on at beginning of row help!

Hi all.
I am knitting a child’s hat, which has a curved front. At the beginning of the new row, the pattern asks me to ‘cast on 27 stitches and knit to end’. The next row (purl) says the same but purl to end. I can cast on stitches to my left needle, but knitting the whole row creates an extra row when it comes to the second part. How can I cast on to the right needle?
Thanks

First of all…what pattern are you making? Can you post a link if possible? (Don’t post the whole pattern)

If you only have a few using the backward loop cast on works, but for that many I’d use the knitted cast on or cable cast on. Turn your work so the stitches are in your left hand and then using the working yarn cast on 27 stitches. There are instructions for both cast ons in at the free knitting video link above.