I love Adobe Captivate's variables and advanced actions. One of my favorite strategies when working with complicated branching and quizzing in projects is to turn off the playbar on key slides via the variable cpCmdShowPlayBar (assign with 0 to turn off, 1 to turn on). I'm guessing that more than a few fellow Captivate developers have used this feature over the years because Captivate 6 has added a brand new quiz feature allowing the playbar to be hidden during a quiz. It is simple to set up. Choose Quiz Preferences > Settings and select Hide Playbar In Quiz.
There's a glass half full/half empty situation for the Hide Playbar in Quiz setting. Not only will the playbar be hidden for every quiz slide, but it will be hidden for any slide that contains a scored object (such as a button included in the quiz).
No points need be assigned. The object just needs to be included in the quiz. Even if there are no actual quiz questions in the lesson, as long as there are scored objects, the Hide Playbar In Quiz setting will work.
This is great if you want all of the slides with scored objects to have no playbar. But if you want that playbar, it can be a bit frustrating. In that scenario, just take the old variable out of your back pocket and use it! You can override the Hide Playbar In Quiz option by setting cpCmdShowPlaybar on entry to a slide, or via a button or advanced action--whatever you prefer. To add the variable on entry to a slide, select the slide on the Filmstrip and, from the Action group of the Properties panel, choose Assign from the On Enter drop-down menu, cpCmndShowPlaybar from the Assign drop-down menu, and then type the number 1 into the With field.