Pitching a Non-Fiction Series

I am doing a pitch at the Storymakers conference for a non-fiction teaching series I am working on. Currently, it's mapped out to be a four book series. Do I tell the publisher this upfront or pitch the first book, then tell them it's part of a series?

Pitching non-fiction is a little different than pitching fiction. In this case, yes, tell the publisher that you would like to do a series but be brief in the details on the other three books unless they ask for more. (Brief = "I see this as a four book series, book one covers ABC, book two covers DEF, ... Here is my proposal for book one ...")

Concentrate on book one because if you don't sell that one, the rest of the series is moot.