Instructions

[kitty 4]

Can anyone tell me, please, which modal verb can be used in a book of teaching method? It instructs teacher to do and not to do.

Ex. write letters in big font.....
Should it be:

You should write letters in big font.

Or

You are to write letters in big font
.....

Thank you

[SoothingDave]

"Fonts" have to do with typefaces, whether printed material, or on a computer screen. If someone is actually writing with their hands, they do not write in fonts.

You should write using big letters.

[Barb_D]

But the imperative is still better, in my opinion.

Write in large letters

This is just as clear (perhaps more clear) than
You should write in large letters.