oral presentation - overhead transparencies (OHTs)

Purpose

The aim of using transparencies is to support the points you want to make in speech. The audience will be able to follow better if they can see your key points and examples as well as hearing them. OHTs can

• Reinforce a point you have made
• Show what something looks like
• Illustrate relationships
• Show information patterns
• Present figures or graphs
• Summarise key points
• Help the audience follow passages or quotations you read aloud

OHTs are not the only form of visual aid available to you. For example, if you want to show what something looks like, it may be better to show the audience the thing itself rather than a picture of it.

Design

To be effective, OHTs must be attractive and easy to read. Some basic rules are:

• Use large fonts and images
• Present one key point or example per OHT
• Use headings and bullet points in preference to lines of text
• Use strong colours and don't use too many
• Use simple graphs in preference to tables of figures
• Pay attention to layout. Use the centre of the OHT rather than the edges

Using overhead projectors

Overhead projectors are designed to allow the speaker to project an image while facing the audience. The image may be a picture or graphic, notes indicating the points you are making or longer texts that you want to read aloud. Whenever you use an OHT, the attention of the audience will be divided between you and the image, so there are a few basic rules to follow:

• Make sure the image can be seen. If possible go to the room in advance and check that everything on your OHTs can be read easily from the back of the room.
• If possible, make sure the projector is in a convenient position. Decide where you want to stand when speaking and then position the projector where you can get to it easily. This will usually be on the side of your body that you normally use for writing (i.e. your left side if you are left-handed)
• Keep your slides in order in a pile next to the projector and put them back in order in another pile as you take them off the projector.
• If possible, control the lighting in the room yourself so that there is always a light shining on you. If your OHTs are easy to read, you will not need to turn off the lights.
• When you are presenting, avoid looking at the projected image and the transparency on the projector. It is a good idea to print out your slides on paper to keep with your notes so you can refer to them while you are speaking.
• If you want to draw attention to a point on an OHT, put a pen on top of it and leave it pointing at the point you want to draw attention to. Don't point with your finger because you will have to look at the projector while you do so.
• If you want the audience to read longer texts on OHTs (e.g. quotations or tables of figures) give them time to do so. There is no point in putting an OHT on the projector if the audience does not have time to read it.
• Make sure you explain the content and purpose of each OHT.

The main rule is to use OHTs to support your talk. Don't let them dominate it.

OHTs and handouts

Some speakers give handouts for the audience to read while they are talking. The advantage of OHTs over handouts is that they focus attention on you and your talk. If you want to give a handout, it is often a good idea to wait until the end of the presentation before distributing it. Often members of the audience want to note down points from your OHTs. This can distract them from following the presentation, so it is a good idea to distribute information that the audience will want to note down on handout. As soon as someone starts taking notes, tell the audience that they do not need to do so because they will get the information on the handout.

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