Every speaker wants to be as convincing as possible with his slides presentation. The better the presentation of the facts about history and the lines of argument, the easier it is for you to win over the audience for your arguments. It is particularly effective to compare a state before an event with the state after it. A before and after comparison works just as well with a presentation.
Before and after slides comparison as a popular principle when presenting topics about history
The before-and-after comparison is useful, for example, if you have to present balance sheets. Instead of hiding the differences in tables or pie charts, you can impress your auditorium by showing extra PowerPoint for comparison. If you are going to show topics about history that needs comparison then presenting this in a slide template is a good idea. For instance, if you want to show a historical place then you may present a before-and-after image. This way, your audience can understand your point better.
The if-then comparison as a variant of the before-and-after comparison
You can also move a comparison into the future and use it for an impressive forecast. This allows you to use an additional variant, the if-then comparison. This enables you to present future scenarios in such a way that the urgency of your argument or your recommendation is particularly easy to understand.
In the beginning, you describe the current status. Then explain what steps need to be taken now and then explain what will happen if nothing is done. Finally, you could come back to the measures you have presented and explain the advantages of following your suggestions and how further hesitation would further adversely affect the current situation.
You can also use the if-then comparison when unpopular measures have to be taken. Nevertheless, there are situations in which tough cuts seem inevitable. Here you can use the before and after comparison principle to show what will happen if no action is taken and what would happen if the plan you presented is implemented.
Whenever you should use a before and after comparison in your slides about history, keep in mind that you can use it to emphasize or underline facts. Nevertheless, you should remain credible and not gamble away the trust of your audience with excessive exaggerations.