I see lots of slide presentations where the person who produced it thinks that a collection of pretty pictures is enough. Generally it is not. There are thousands of superb pictures on sites all over the world wide web. Slideshows and presentations are rarely about the pictures. Mostly, a slideshow's purpose is to convey a message or tell a story.

So, before you start assembling an assortment of images let's talk more about the story. There are three main considerations here:

• What do I want to say?

• What is my intended audience?

• How long have I got to get my message across?

As a story I will choose the idea that in the city of Preston, UK. They are thinking of building a new bus station. The present building won awards when it was completed in the 1960s but it doesn't meet the needs of the 21^st century. And, I am going to introduce 2 audiences. These are:

• Architects and Town Planners

• A primary school class of 6-7 year old children in an outlying district of the city

As you can see such disparate groups will need entirely different slideshows. All stories need to start with something the audience knows or recognises. So, although the subject of the slideshow the approach to each will be entirely different.

For the school children the slideshow could, in England, form part of their learning towards Key Stage 1 'Geography' and as a public relations exercise in showing what the proposed future will look like. Strangely enough, many of the children will not have used public transport having been ferried to and fro by car. But, of course, they see buses in the streets of Preston: one route passes the school. So that may make a good starting point.

The adult audience's slideshow requires just as much attention to detail but it shouldn't be a case of teaching grandma to suck eggs. One of the main problems with bus stations is access: how do you get buses in and out of the site remembering that it will inevitably be a town centre location, and how do passengers access the site safely? What other facilities do you need or want to provide? And, of course, the biggest question of all, how will it provide for the city's needs in 20 years time?

The formats of each slideshow should be different too. You may wish for architects and town planners to have their own copies for reference so a presentation that runs automatically and has its own recorded audio is a better option. With the one for the children it starts at such a basic level that it may mean that several slideshows are required as a child's attention span is not very long. Also it will probably work better if the teacher has control over the duration that each picture is shown and provide blanks when the children's attention needs to be concentrated on the teacher.

For the school presentation each part can consist of individual picture files numbered sequentially and the parts in different folders. The Architects and Planners slideshow is best recorded in a standard video format so it can be viewed on a TV or via a computer. (Personally, I would also provide individual picture files so that the Architects and Planners could integrate them into a slideshow with their proposals.)