Answer:
Firstly, why is this even a question? Oh well.
A slide show compared to an essay can further your students' understanding of the material being taught to them, as they can see with photos, illustrations of the period, archive footage, and other helpful media to give them the full picture. An essay a student may not even be interested in reading, and they can't get the "characters" of the subject in their heads. In history or social studies, the goal is to give the learner a clear view of the subject and give an unbiased education that is thorough to them. A slide show can help this goal be a reality, both for the presenter and the learners.
This should be able to give you a good start. Make sure to put it in your own words unless your teacher allows you to use mine.
