Margins

What would be the correct margins for a 8.5x11 student workbook?

1 inch would be standard.

Should there be a bigger margin on the inside towards the binding?
I made it .5" all around and .75" on the inside edge. Think that’s fine?

.75" is usually the minimum for the bound side; the other sides don’t really matter technically, more a design consideration. 1" is the standard for most workbooks of that size, but that is mainly a design consideration other than the bound side. If you want to be sure, always best to contact the printer in case they have specific requirements.