Q1. When you were talking about “Thing to keep in mind when making & using worksheets”, the second one was “Not all worksheets should be written on - some worksheets you provide to your student might just be completely filled out & they should write their own notes & answers on another piece of papers ??” I can’t get it. Could you explain more about it? 

Additionally, I’m curious the reason why we should build up a bunch of worksheets? Is it in case we can use it again for another class?