The orators of ancient Greece and Rome and American presidents Abraham Lincoln and John F. Kennedy had little more than voice and body language to help them, and they seem to have done just fine. But if you can better explain information with graphics, then the easiest to use are erasable blackboards or whiteboards and flip charts (pads of paper on easels).

Ideally, blackboards should be prepared in advance of the lecture, especially if you need to do any drawing that has to be accurate and may take some time. Try to hide what you have written or drawn until you need to show it, lest it distract your listeners. And be sure that there is adequate chalk and an eraser on hand.

The rules for whiteboards and flip charts are similar. The key things to remember for optimum use:

• Use black, blue, green, and red markers (be sure to have extras).

• Write legibly or get help.

• Only write on the top two-thirds of the paper, to be sure everyone in the back rows can see your points.

• The main limit to using flip charts and whiteboards is the size of the audience, so make letters as tall and thick as is appropriate. A letter that is 1½ inches tall and reasonably thick can be seen well enough at about thirty feet.

Although one of the advantages to using flip charts is that you can keep using them over and over, do not hesitate to change anything on the spot, if you discover that a point is not clear to the audience or is effectively challenged. If you do not mind redrawing simple charts, you can also make them more dynamic by adding words, arrows, or underlining as you talk.

You can also use blank pages to get the audience to participate, such as to brainstorm ideas for promoting a new product or to think of possible solutions to a problem. In this respect, it is more interactive than other visual aids.