How to Make Soap to Use Up Old Oils

I’ve wanted to make soap for a while … 🧼
This could be a good starting point:
https://www.ellyseveryday.com/ellys-everyday-blog/how-to-make-soap-using-up-old-oils

And it would be a fun kids activity that teaches chemistry and they get to *use* the soap day-to-day. 💭