To answer the last part of your question – where someone told you that you should avoid using the term blackboard – there is a difference between a blackboard and a whiteboard; the two terms refer to different prodcutsproducts.
Blackboard vs. whiteboard
A blackboardblackboard, also called a chalkboard, is usually black or dark green and is meant to be written on using chalk.
blackboard http://upload.wikimedia.org/wikipedia/commons/3/34/Math_lecture_at_TKK.JPG
A whiteboard is a smooth white plastic-coated board, meant to be written on using a felt pen.
whiteboard — "Blank whiteboard" by BrokenSphere - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0-2.5-2.0-1.0 via Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/5/5c/Blank_whiteboard.JPG
Blackboards and whiteboards are different things. Whiteboards are starting to displace blackboards due to chalk allergies, among other reasons. However, referring to a blackboard as a "whiteboard" due to racial sensitivity is silly political correctness gone wild. If you really need a euphemism, call it a chalkboard.