If a course designer has established a 10 pt font, they are on their way to serious frustration. The concept of a fixed-size font is related to printed material, so it should go along with establishing a paper size for eLearning. How many points are there on the end-users screens?
Good web practice dictates that you should use a relative size font. The base font size should be the end-user's choice. In MS-IE, you can go under Tools, and find the button for "Size". In Firefox and other Mozilla browsers, the learners can select their base font size much more freely. Why does this matter? For accessibility. A 10 pt font may be fine on an 800x600 pixel screen, but it is too large for a PDA, and it is too small if the end-user has visual disabilities or they have a 1600x1200 19-inch screen. Instead, the font size should be specified as a percentage of the end-user's default (e.g. 100%, 80%, 120%, etc.)
With web pages, it is also important to select:
1. Acceptable combinations of foreground and background color (if there is not enough contrast, the font will be illegible).
2. Acceptable foreground colors: Keep in mind that in many cases the end user may turn off images and background images (like on a Blackberry). If you choose a white foreground font with a dark background image, the text will be invisible because the PDA or other rendering device will provide a white background. (So use dark colors.)
3. Relative font sizes, font families, text decoration, etc. for different elements of the page, e.g. Heading, summary section, test question, test answer, test distractor, Outline numbering, ... I recommend that a read-through of the Cascading Style Sheets specification be made before going much further with this exercise.
4. Define navigation graphics (forward, back, glossary, test, try-this)
5. Define navigation texts ("next", "back", "Grade the Test", "Submit Survey Responses").
It would be worthwhile to review a complete web-based eLearning course (not a PowerPoint presentation displayed through the web) to see all the different kinds of elements that will be used. Otherwise, the specification of a 10 point sans-serif font for "eLearning" is like saying, "I want to use blue paper for Word documents."