How do I best communicate text and graphics I write on the board or present in PowerPoint during lectures to a student who is blind?

When writing text or equations on the board or in PowerPoint, it is important to clearly say aloud what is being written. When mathematical expressions and formulae are involved, attention to detail, such as capitalization and the placement of parentheses, is crucial. If graphs are presented, the features relevant to the material being covered should be described during the lecture. Avoid vague terms such as "this", "that", "here", and "there".