Changing from knit to purl mid row - extra stitches appear!

I am learning to knit and can now knit and purl full rows of each stitch. Now I am trying to knit a pattern for a dishcloth that requires that I knit a certain number of stitches then change to purl stitch mid-row.

Each time I change to or from purl I end up with an extra stitch appearing on my needle! I have watched several videos on-line about how to knit and how to purl to check that I'm doing that right, and it seems that I am.

What am I doing wrong?

YOUR ANSWER

When you have done the required number of knit stitches you need to move the trailing yarn from the back of the work to the front. I suspect that what you are doing is wrapping the yarn around or over the needle when you are moving from knit to purl and vice versa.

What you need to do is to move the yarn between the two needles and make sure that it is lying underneath the right hand needle before you do your first purl stitch. What I usually do is separate the tips of the two needles and pull the yarn between them. Then you slip the right hand needle into the front of the first stitch on the left hand needle for the first purl.

The yarn should be at the front and underneath the right hand needle.