Related: How can I close my sessions better?
I'm an inexperienced DM running my second game (playing D&D 5e both times).
The first game I ran was the Starter Set, 'Lost Mine of Phandelver', with players who had a combined total of almost 40 years RPing experience. They knew how adventures worked and could use their experience to pick up on what goals were being presented.
My current game is with 4 totally new roleplayers. I'm finding it difficult to let them know (without giving plot away) what the size of the adventure they're playing is.
For example, when running episode 1 of 'Hoard of the Dragon Queen' as a 'one night only' game, I got to the end of the episode and the players all wanted to continue straight on following the plot hooks into episode 2.
When running an introductory adventure of my own making for them (which was intended as a one-day-only game but spilled over into a second night) they picked up on and wanted to immediately follow the plot hooks at the end before we'd even spoken about whether they all wanted to continue in a regular game.
One of my players has told me she finds it useful to always have a goal in mind for whatever she's doing, and to know what the structure of her plan is. I, too, feel that my role as DM would be easier knowing there were specific parts of a story my players were progressing through - for example, so I knew when a good time to level up would be (using milestone leveling), and because all the published adventures I've read have had this structure.
So, How do I, without giving away plot in advance, let the players know what the adventure is going to consist of, so that they know when they've finished it?