Take 1

While some consider overhead projectors more reliable, it is important to effectively manage this medium.  Unless you have extremely legible handwriting, type the overheads with a large font.  Occasionally glance at the screen to make sure the slide is placed properly.

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Take 2

Here the presenter uses an easy-to-read typed font, keeps his body clear of the projection, and carefully positions the slides on the projector.  He also uses a pen to point to key parts of the slide.

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