I'm making a commercial course on graphic design and one of the sections I go over the types of logos like IBM/CNN/HP/NASA are Lettermark based logos.
My question more so is how can I legally use these logos in my course?
Sounds like you are including the logo so you can provide commentary on it, so this would likely come under "Fair Use". Fair use covers circumstances that allow copyrighted material to be used without permission, and examples include commentary, criticism, parody, etc.
The specific rules vary by country.
Seach "Fair Use" for more information.