I'm making a slide show presentation in InDesign.
Simply I have a page with many dot points, and want each single one to appear on click as I'm talking.
Is there a way to make objects appear on click in an Interactive PDF when set up in InDesign?
I was instead going to put each new dot point on a new page - but it seems excessive.
I don't know how InDesign handles interactive documents, my InDesign documents all go to a printer, so I've never experimented with that part of ID. However, in general there are several ways you can show items based on mouse clicks. You've already mentioned one: Having one page per step in your "reveal". This is the method that will always work, regardless of what system you use to view the presentation.
You can use form fields and "wrap" your hidden elements that you want to reveal in e.g. an interactive button, which can show a PDF page or an image once it's display property is set to being visible. This would however require that you take apart your page and isolate the elements that you want to hide/show and then package them up in buttons and add the logic that would show one after the other when you click on the page.
Unless your application has built-in support to create PDF documents with that functionality already added to the PDF file, using one page at a time is very likely the least complex and time consuming method.