Outline slides in scientific talks are unnecessary and cut into a speaker’s valuable time. Many scientific talks are 10–12 minutes, and spending a whole slide outlining the next 10 minutes is pointless. Why? Because your talk is very likely going to follow a standard order: You’ll start with some motivation, move onto the background, present your results, then finish up with what you have concluded. This is what the audience is expecting, so don’t need to waste time reiterating. As an audience member, I prefer you use this time to teach me something.
Add a sidebar
Despite advising against an outline slide, I recommend adding an outline of your talk in a sidebar on all of your slides. In talks I give, the slides on my sidebar will look something like this (with less generic labels and actual content):
A benefit of the sidebar is that it gives the audience an indication of how far through your talk you are. (If I had a dollar for every time I wondered how much longer a talk would go for…)
I use LaTeX Beamer to create my slides. My template is available here. A subtle bonus that comes by default is that the sidebar labels are hyperlinks to their respective slides within the PDF. No need to backtrack through every slide if you want to find a particular one at the end of your talk. Instead, just click the appropriate section label and you’ll find your slide in no time.