See https://practicaltypography.com/point-size.html.

It is not Microsoft Word that has the concept of points, it is typography.

There are 72 points in an inch and a 12-point font should be 1/6 of an inch high. However, it is up to the maker of the font to fit that considering ascenders, descenders, and space between lines.

What is it you are trying to teach your students with this tool?

Times New Roman is not a good font to be teaching them to use. Try Garamond instead.