Hi. I have been asked to give my opinion on the topic of the use of the Nemeth asterisk as a multiplication sign in a 3rd grade workbook.
As far as I know, Promising Practices (guidelines for K-3 braille materials) does not address this.
As a braille transcriber, we are to braille what we see, following rules in the Nemeth Codebook and the BANA 2007 Update.
Certainly if this workbook is being brailled for production, you would not change the asterisk to a multiplication dot.
If, on the other hand, you are (or are working for) a Teacher of the Visually Impaired and are producing the workbook for a specific student and *only for that student, and the teacher has expressly asked you to use the multiplication dot instead of the asterisk, I would follow the teacher's request. HOWEVER, this is not Code, and should not be common practice.
PLEASE NOTE: The asterisk is used as the multiplication symbol when students are using a calculator. The asterisk is the symbol on the calculator keypad, and that is the symbol we braille, using NC keystroke notation. I would not change the asterisk to a multiplication dot in exercises that are meant for calculator practice.