Binding off in crochet

when I fasten off my crocheting I cut the yarn, slip stitch and pull yarn through and pull tight. I remember that I used to fasten off another way and when I saw this way of fastening off I wasn't so sure about pulling the yarn all the way through. I'm teaching crochet and at some point we'll be fastening off our work so I was looking on how to fasten off. I know this new way as I stated above but I don't remember the old way. I thought I should show the people I'm teaching how to fasten off the old way to do it. In looking on how to do this I came across something interesting. Instead of binding off with 2 knitting needles you can use a knitting needle and a crochet hook. After you click on the website or copy and paste it into your browser scroll down past that video that you see and go to where it says: People also ask and go to the question How do you bind off in crocheting? and click on the arrow that's on the right side of the above question and watch the video.

fastening off crochet - Google Search

The old way of fastening off made a knot or left a knot.

I think I remember how I did it. After cutting the yarn I believe I pulled the yarn through the chain stitch but that would be pulling the yarn all the way through if I was going to end up with a knot.?